Document:

REVOLVING LINE OF CREDIT AGREEMENT

                                 by and between

                                  BIOTIME, INC.
                                  as "Borrower"

                                       and

                               ALFRED D. KINGSLEY
                                   as "Lender"

                           Dated as of March 27, 2002

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                                TABLE OF CONTENTS

1.  General Definitions...................................................1

2.  Draws and Disbursements...............................................2

3.  Terms of Payment......................................................4

4.  Warrant...............................................................5

5.  Events of Default.....................................................5

6.  Remedies On Default...................................................6

7.  Representations and Warranties of Borrower............................6

8.  Affirmative Covenants.................................................8

9.  Fees and Charges of Attorneys and Others..............................9

10. Maximum Permitted Interest...........................................10

11. Governing Law........................................................10

12. Successors and Assigns...............................................10

13. Entire Agreement; Amendment..........................................10

14. Survival.............................................................10

15. Notices..............................................................10

16. Delays and Omissions.................................................11

17. Rules of Construction................................................11

18. Severability.........................................................11

19. Counterparts.........................................................12

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                       REVOLVING LINE OF CREDIT AGREEMENT

         This Revolving Line of Credit  Agreement  ("Credit  Agreement") is made
and  entered  into as of March 27,  2002,  by and  between  Alfred  D.  Kingsley
("Lender"), and BioTime, Inc., a California corporation ("Borrower").

                                    RECITALS

Borrower  has  requested a credit  facility  consisting  of a revolving  line of
credit, and Lender is willing to make the requested credit facility to Borrower,
but only upon the terms, and subject to the conditions, contained herein.

                                    AGREEMENT

Now,  therefore,  in  consideration  of the  premises  and the mutual  covenants
hereinafter contained, the parties hereto agree as follows:

         1. General  Definitions.  The following  words shall have the following
meanings:

                  1.1  "Business  Day" means any day that is not a  Saturday,  a
Sunday, or a day on which banks are required, or permitted,  to be closed in the
State of New York.

                  1.2 "Credit Facility" means the right of Borrower to borrow up
to $300,000 from Lender under the terms and conditions of this Credit  Agreement
and the Note.

                  1.3  "Debtor  Relief  Law"  means the  Bankruptcy  Code of the
United  States of America,  as  amended,  or any other  applicable  liquidation,
conservatorship,    bankruptcy,   moratorium,    rearrangement,    receivership,
insolvency, reorganization, or similar debtor relief law affecting the rights of
creditors generally.

                  1.4 "Event of Default" or "Events of Default" means any of the
events specified in Section 5, 19.

                  1.5 "Loan" means the loans made by Lender to Borrower pursuant
to this Credit Agreement, and evidenced by the Note.

                  1.6 "Loan  Documents" means this Credit  Agreement,  the Note,
the Warrant Agreement, and all other agreements,  instruments,  and documents in
favor of Lender,  now or  hereafter  executed  by or on behalf of  Borrower  and
delivered to Lender in  connection  with this Credit  Agreement or in connection
with any of the transactions contemplated hereby.

                  1.7  "Maturity  Date" means the earlier of (i) March 31, 2003,
and (ii) such  date on which  Borrower  shall  have  received  an  aggregate  of
$600,000  through (A) the sale of capital  stock,  (B) the collection of license
fees, signing fees, milestone fees, or similar fees under

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Borrower's  Exclusive  License  Agreement with Abbott  Laboratories or under any
other present or future agreement  pursuant to which Borrower grants one or more
licenses to use Borrower's patents or technology,  (C) funds borrowed from other
lenders, or (D) any combination of sources under clauses (A) through (C).

                  1.8 "Note" means the  promissory  note,  of even date,  in the
form attached as EXHIBIT A, evidencing the Loan to be executed concurrently with
this Credit Agreement.

                  1.9 "Warrant"  means the stock  purchase  warrant issued under
the Warrant  Agreement  attached as EXHIBIT B,  entitling the holder  thereof to
purchase common shares of the Borrower.

         2. Draws and Disbursements.

                  2.1 Maximum Loan Amount. On the terms and conditions set forth
in this Credit  Agreement,  Lender  shall make  available to Borrower the Credit
Facility,  as a revolving line of credit in a principal  amount not to exceed at
any one time Three  Hundred  Thousand  Dollars  ($300,000),  less all amounts of
principal  prepaid or required to be prepaid  under Section 3.2.1 of this Credit
Agreement (the "Maximum Loan Amount").

                  2.2 Draw Period.  Borrower may request from Lender advances of
funds  ("Draws") under the Credit Facility from the date of this Agreement until
March 1, 2003 (the "Draw  Period").  As amounts drawn by Borrower  hereunder are
repaid,  they may be  reborrowed  subject  to the terms and  conditions  of this
Credit Agreement; provided, that at no time shall the aggregate principal amount
of Loans outstanding under this Credit Agreement exceed the Maximum Loan Amount.
The Draw Period may be terminated  by Borrower at any time by written  notice to
Lender.  Subject  to the terms and  conditions  of this  Credit  Agreement,  and
provided  that no Event of Default has  occurred,  Lender shall make advances to
Borrower  upon request as provided in this Section 2. Upon the  occurrence of an
Event of, one of Lender's remedies includes Lender's right to terminate the Draw
Period and Borrower's right to make Draws under this Credit Agreement.

                  2.3  Increments.  Draws must be in increments of not less than
One Hundred Thousand Dollars ($100,000), or the remaining amount available under
the Credit Facility, whichever is less.

                  2.4  Use of  Funds.  All  funds  borrowed  under  this  Credit
Agreement will be used as working  capital to pay Borrower  expenses  arising in
the ordinary course of business.

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         2.5 Disbursement Procedures.

                           2.5.1 Borrower  hereby  appoints its Chief  Executive
Officer,  President,  and Chief Financial Officer as the officers  authorized to
make Draws under this Credit Agreement  during the Draw Period.  Any one of such
officers (the "Authorized Officers") is authorized to make Draws. Lender, at its
sole option, may require that all requests for Loan funds be in writing,  signed
by an Authorized  Officer,  in a form acceptable to Lender.  Facsimile documents
may be accepted by Lender as originals.  Any Draw by an Authorized Officer shall
constitute an ongoing  representation  and warranty by Borrower that at the time
of request for or payment of any Draw no Event of Default has occurred.

                           2.5.2 Draws shall be paid according to the Authorized
Officer's instructions,  except that checks representing Loan funds shall always
be made  payable to  Borrower,  and wire  transfers  shall only be  permitted if
Borrower has authorized  payment into the account into which the funds are to be
deposited. The appointment of the above-named Authorized Officer(s) shall remain
in full force and effect  until  written  notice of  revocation  of  appointment
signed by the Chief Executive Officer or Chief Financial Officer of Borrower has
been received by Lender.

                           2.5.3 Lender shall advance Loan funds available under
the Credit Facility in accordance with Borrower's Draws within four (4) Business
Days after the receipt of the Draw.

                           2.5.4   Each  Draw  shall  be   accompanied   by  the
certificates required by Section 2.6.

                           2.5.5  Borrower  shall   indemnify  and  hold  Lender
harmless  from loss or  liability  of any kind  arising  from or  related to any
action or inaction  taken by Lender in good faith in reliance upon  instructions
received from any Authorized Officer.

         2.6 Conditions  Precedent.  The following  conditions must be satisfied
before Lender shall be obligated to disburse Loan funds to Borrower  pursuant to
a Draw:

                           2.6.1 Due execution.  Lender shall have received duly
originals of this Credit Agreement and all other Loan Documents.

                           2.6.2 Approvals.  Lender shall have received evidence
satisfactory  to it that all consents and approvals  which are necessary for, or
required as a  condition  of, the  validity  and  enforceability  of this Credit
Agreement and all other Loan  Documents have been obtained and are in full force
and effect.

                           2.6.3  Representations and Warranties Correct. All of
Borrower's representations and warranties contained in this Credit Agreement and
in any other Loan Document shall be true and correct in all material respects on
the date the Loan funds are

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disbursed, and Borrower shall have delivered to Lender a certificate executed by
an Authorized Officer to such effect.

                           2.6.4 No Event of Default.  No Event of Default shall
have  occurred,  and  Borrower  shall  have  delivered  to Lender a  certificate
executed by an Authorized Officer to such effect.

                           2.6.5 Independent Verification. Borrower must provide
for Lender's  review and  acceptance  such  documentation  as may be required by
Lender to ensure Borrower is in compliance with the terms and conditions of this
Credit Agreement, including, without limitation, resolutions of Borrower's board
of directors or a duly constituted and authorized  committee thereof,  certified
by the secretary or an assistant  secretary of the corporation,  authorizing the
execution  and  delivery  of this  Agreement  and the other Loan  Documents  and
performance of Borrower's obligations hereunder and thereunder.

                           2.6.6  Warrant.  Prior to the initial Draw under this
Credit  Agreement,  Borrower must have executed the Warrant Agreement and issued
the Warrant to Lender.

                           2.6.7  Closing  Costs.  Borrower  must  have paid all
attorneys' fees incurred by Lender in connection the preparation, execution, and
delivery of the Loan Documents, and all reports and notices required to be filed
by Lender  or its  affiliates  under the  Securities  Exchange  Act of 1934,  as
amended, in connection with this Agreement and Lender's receipt of the Warrant.

         3. Terms of Payment.

                  3.1 Interest. Interest shall accrue and be payable at the rate
of 10% per annum on the  outstanding  principal  balance  of the Loan.  Interest
shall accrue from the date of each disbursement of principal pursuant to a Draw.
Accrued  interest shall be paid with  principal on the Maturity  Date.  Interest
will be charged on that part of outstanding  principal of the Loan which has not
been paid and shall be  calculated  on the basis of a 360-day  year and a 30-day
month.

                  3.2 Payment of Principal. The outstanding principal balance of
the Loan, together with accrued interest,  shall be paid in full on the Maturity
Date.

                           3.2.1 Mandatory Prepayment of Principal. In the event
that  Borrower  receives,  in the  aggregate,  an  amount  of funds in excess of
$300,000  but less than  $600,000  from (A) the sale of capital  stock,  (B) the
collection of license fees, signing fees,  milestone fees, or similar fees under
Borrower's  Exclusive License Agreement with Abbott  Laboratories,  or under any
other present or future agreement  pursuant to which Borrower grants one or more
licenses to use Borrower's patents or technology,  (C) funds borrowed from other
lenders,  or (D) any  combination  of sources  under  clauses (A)  through  (C),
Borrower  shall use the funds in excess of  $300,000 to prepay  principal,  plus
accrued interest, within two business days after such funds are

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received by Borrower,  and the amount of  principal so prepaid  shall reduce the
Maximum Loan Amount.

                           3.2.2 Optional Prepayment of Principal.  Borrower may
prepay principal, with accrued interest, at any time and the amount of principal
so prepaid  shall be  available  for further  Draws by Borrower  during the Draw
Period to the extent that the  prepayment  of principal  was not required  under
Section 3.2.1.

                  3.3 Default  Interest Rate; Late Payment Charge.  In the event
that any payment of  principal or interest is not paid within five (5) days from
on the date on which the same is due and payable, such payment shall continue as
an obligation of the  Borrower,  and interest  thereon from the due date of such
payment and interest on the entire unpaid balance of the Loan shall accrue until
paid in full at the lesser of (i) fifteen  percent (15%) per annum,  or (ii) the
highest interest rate permitted under applicable law (the "Default Rate").  From
and after the Maturity Date or upon  acceleration of the Note, the entire unpaid
principal balance of the Loan with all unpaid interest accrued thereon,  and any
and all other fees and charges then due at such maturity, shall bear interest at
the Default Rate.

                  3.4  Date of  Payment.  If the  date on  which  a  payment  of
principal  or  interest  on the Loan is due is a day other than a Business  Day,
then payment of such principal or interest need not be made on such date but may
be made on the next succeeding Business Day.

                  3.5  Application  of Payments.  All payments  shall be applied
first to costs of  collection,  next to late charges or other sums owing Lender,
next to accrued  interest,  and then to  principal,  or in such  other  order or
proportion as Lender, in its sole discretion, may determine.

                  3.6  Currency.  All  payments  shall be made in United  States
Dollars.

         4. Warrant. As consideration for Lender making Credit Faculty available
to Borrower, Borrower will issue and deliver Lender a Warrant to purchase thirty
thousand (30,000) common shares, no par value of Borrower. The exercise price of
the Warrant will be $4.00.

         5. Events of Default. The following shall constitute Events of Default:
(a) the  default of Borrower in the  payment of any  interest or  principal  due
under this Credit  Agreement or the Note; (b) the failure of Borrower to perform
or observe any other term or provision of, or covenant, agreement, or obligation
under, this Credit Agreement or any other Loan Document;  (c) any act, omission,
or other event that  constitutes  an "Event of Default"  under the Note; (d) any
representation or warranty of Borrower  contained in this Credit Agreement or in
any other Loan Document, or in any certificate delivered by Borrower pursuant to
this Credit Agreement or any other Loan Document,  is false or misleading in any
material  respect when made or given;  (e) Borrower  becoming the subject of any
order for relief in a  proceeding  under any Debtor  Relief  Law;  (f)  Borrower
making an assignment for the benefit of creditors;  (g) Borrower applying for or
consenting to the appointment of any receiver, trustee, custodian,  conservator,
liquidator,  rehabilitator,  or similar officer for it or for all or any part of
its property or assets; (h) the

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appointment  of  any  receiver,  trustee,  custodian,  conservator,  liquidator,
rehabilitator,  or similar  officer for Borrower,  or for all or any part of the
property or assets of Borrower,  without the application or consent  Borrower if
such  appointment  continues  undischarged  or unstayed for sixty (60)  calendar
days; (i) Borrower  instituting or consenting to any proceeding under any Debtor
Relief  Law with  respect to  Borrower,  or all or any part of its  property  or
assets, or the institution of any similar case or proceeding without the consent
of Borrower,  if such case or proceeding  continues  undismissed or unstayed for
sixty (60) calendar days; (j) the dissolution or liquidation of Borrower, or the
winding-up of the business or affairs of Borrower;  (k) the taking of any action
by Borrower to initiate any of the actions  described in clauses (f) through (j)
of this paragraph;  (l) the issuance or levy of any judgment,  writ,  warrant of
attachment or execution or similar  process  against all or any material part of
the property or assets of Borrower if such process is not  released,  vacated or
fully bonded within sixty (60) calendar days after its issue or levy; or (m) any
breach or default by Borrower under its Exclusive  License Agreement with Abbott
Laboratories,  the  occurrence  of an Event of Default under  Borrower's  Series
2001-A  Debentures,  or any  breach  or  default  by  Borrower  under  any  loan
agreement,  promissory note, or other instrument evidencing indebtedness payable
to a third party.

         6. Remedies On Default.  Upon the occurrence of an Event of Default, at
Lender's  option,  all unpaid  principal  and  accrued  interest,  and all other
amounts  payable under this Credit  Facility and any other Loan  Document  shall
become  immediately  due and  payable  without  presentment,  demand,  notice of
non-payment, protest, or notice of non-payment. Lender also shall have all other
rights,  powers, and remedies available under this Credit Agreement and the Note
or any other Loan Document, or accorded by law or at equity. All rights, powers,
and  remedies of Lender may be  exercised at any time by Lender and from time to
time after the  occurrence  of an Event of  Default.  All  rights,  powers,  and
remedies of Lender in connection with this Credit Agreement and the Note and any
Loan Document are  cumulative  and not exclusive and shall be in addition to any
other rights, powers, or remedies provided by law or equity.

         7. Representations and Warranties of Borrower.  Borrower represents and
warrants to Lender the following:

                  7.1  Organization;  Capitalization.  Borrower is a corporation
duly  organized,  validly  existing and in good  standing  under the laws of the
state of California and has all requisite  corporate  power and authority to own
its property and to carry on its business as now being conducted.

                  7.2  Authority;  Enforceability.  Borrower  has the  power and
authority  to execute and deliver  this Credit  Agreement  and each of the other
Loan Documents,  and to perform all of Borrower's  obligations under this Credit
Agreement and the other Loan  Documents.  This Credit  Agreement and each of the
other Loan  Agreements  is the valid and binding  agreement  and  obligation  of
Borrower,  enforceable in accordance  with its respective  terms,  except to the
extent  limited by any  bankruptcy,  insolvency,  or similar law  affecting  the
rights of creditors generally. There are no corporate,  contractual,  statutory,
regulatory,  judicial,  or other  restrictions  of any kind  upon the  power and
authority of Borrower to execute and deliver this Credit  Agreement or any other
Loan Document,  and to consummate the  transactions  contemplated by this Credit
Agreement and the other Loan Documents,  including,  without limitation: (a) the
payment of all principal  and interest that may become due on the Loan;  and (b)
the issuance of the Warrant and common shares  issuable upon the exercise of the
Warrant.  No action,  approval or consent by, or notice to or filing  with,  any
federal, state, municipal or other governmental department,  commission, agency,
regulatory authority, or court is necessary to make this Credit Agreement or the
other Loan  Documents the valid  agreements  binding upon Borrower in accordance
with

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their respective  terms, or to consummate the transactions  contemplated by this
Credit Agreement and the other Loan Documents.

                  7.3 No  Conflict.  The  execution  and delivery of this Credit
Agreement and the other Loan Documents, and the consummation of the transactions
contemplated by this Credit  Agreement and the other Loan Documents,  do not and
will not (a) violate any  provisions of (i) any rule,  regulation,  statute,  or
law, or (ii) the terms of any order,  writ or decree of any court or judicial or
regulatory  authority or body, or (iii) the Articles of  Incorporation or Bylaws
of  Borrower,  and (b) conflict  with or result in a breach of any  condition or
provision  or  constitute  a  default  under  or  pursuant  to the  terms of any
contract,  mortgage,  lien, lease,  agreement,  debenture or instrument to which
Borrower  or any  Subsidiary  is a party,  or which is or purports to be binding
upon Borrower, any Subsidiary,  or upon any of their respective properties,  and
(c) result in the creation or imposition of any lien, charge or encumbrance upon
any of the assets or properties of Borrower or any Subsidiary.

                  7.4 Warrant  and  Warrant  Shares.  The  Warrant,  when issued
pursuant to this Credit Agreement, will be a duly authorized, valid, and binding
obligation of Borrower,  enforceable in accordance  with its terms.  When issued
and sold upon the  exercise of the  Warrant in  accordance  with its terms,  the
common shares of the Borrower will be validly issued and outstanding, fully paid
and non-assessable.

                  7.5 Accuracy of Information.  Borrower has delivered to Lender
a copy of  Borrower's  financial  statements  for the year ended on December 31,
2001,  as will be  included in its Form 10-K for such  fiscal  year,  its annual
report on Form 10-K for the fiscal year ended  December 31, 2000,  and quarterly
report on Form 10-Q for the fiscal  quarter and nine months ended  September 30,
2001 (the "Disclosure  Documents").  The financial  statements  contained in the
Disclosure  Documents  were  prepared  in  accordance  with  generally  accepted
accounting   principles,   consistently  applied,  and  accurately  reflect  the
financial condition and results of operations of Borrower at and as of the dates
reported.  All  financial  information  and other  information  contained in the
Disclosure  Documents  was true and correct in all material  respects  when such
reports were filed under the  Securities  Exchange Act of 1934,  as amended (the
"Exchange Act"), and in the case of the financial statements for the fiscal year
ended  December  31, 2001,  is true and correct in all material  respects on the
date of this Credit Agreement, except for changes arising from operations in the
ordinary course of business since December 31, 2001.

                  7.6 Taxes. Borrower has filed when due all federal,  state and
local  income tax returns and has filed when due all other  returns with respect
to taxes which are  required to be filed with the Internal  Revenue  Service and
the appropriate authorities of the jurisdictions where business is transacted by
them.  All items and  entries  provided  for or  reflected  in such  returns are
correct and are made on a proper  basis.  All  amounts,  if any,  required to be
paid,  as shown on such  returns,  have been paid.  None of such tax returns has
been audited. There are no suits, actions, claims, or investigations,  inquiries
or proceedings  now pending against  Borrower in respect of taxes,  governmental
charges or assessments, nor are there any matters under discussion

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with any  governmental  authority  relating  to taxes,  governmental  charges or
assessments asserted by any such authority.

                  7.7   Litigation.   Except  as  disclosed  in  the  Disclosure
Documents,  there  are  no  lawsuits,  arbitration  proceedings,  administrative
proceedings,  actions or claims pending or threatened against Borrower. No fine,
penalty or other  sanction  has been  imposed by any  federal,  state,  local or
municipal  court,  judicial,  administrative  or  regulatory  body or  authority
against Borrower.  There is no outstanding order, writ,  injunction or degree of
any court,  administrative  agency or governmental body or arbitration  tribunal
against or  affecting  Borrower  or any of its  respective  properties,  assets,
business or prospects.

         8. Affirmative  Covenants.  During the Draw Period, and until such time
as the entire principal  balance and accrued interest on the Loan, and all other
amounts  payable by  Borrower  under  this  Credit  Agreement  or any other Loan
Document  have been  paid in full,  Borrower  shall  comply  with the  following
covenants and agreements:

                  8.1 Furnish  Information.  Borrower will, at Lender's request,
furnish  information  to Lender  relating to  Borrower's  business and financial
affairs and permit Lender to examine Borrower's books and records.

                  8.2 Other Documents. Borrower will execute all other documents
as Lender may reasonably  require in connection  with this Credit  Agreement and
Note in order to perfect its lien or security  interest in any of the collateral
for the loan,  or  otherwise to give effect to the terms and  conditions  of the
loan or guaranty for the loan.

                  8.3 Comply  with Terms and  Conditions.  Borrower  will comply
with all terms and conditions of all other Loan Documents.

                  8.4 Financial Reports.  Borrower will file with the Securities
and  Exchange  Commission,  when due, all  quarterly  reports,  annual  reports,
current reports,  and other documents  required pursuant to the Exchange Act and
within 5 days of the date such reports and other documents are so required to be
filed, to mail to Lender a copy of such reports.

                  8.5  Limitation  on  Dividends  and  Other   Distributions  by
Borrower.  Borrower shall not declare or pay any dividend or other  distribution
of cash,  other property,  or evidences of  indebtedness,  on account of or with
respect to any shares of capital stock.

                  8.6 Insurance. Borrower will, and will cause its Subsidiaries,
to maintain  insurance with responsible  carriers against such risks and in such
amounts as is customarily  carried by similar businesses with such deductible as
are  customarily  carried by similar  businesses  of  similar  size,  including,
without  limitation,  property  and casualty  loss,  workers'  compensation  and
interruption of business insurance.

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         9. Fees and Charges of Attorneys  and Others.  In the event that Lender
employs attorneys, accountants,  appraisers,  consultants, or other professional
assistance,  including the services of any such person who is a direct  employee
of Lender, in connection with any of the following,  then, the reasonable amount
of costs,  expenses,  and fees  incurred  by Lender  shall be payable on demand.
Lender  may,  at its  option,  add the  amount  of  such  costs,  expenses,  and
reasonable  fees to the  principal  amount of the Loan.  Lender  thereafter  may
charge  interest  on such amount at the  interest  rate then  applicable  to the
principal. Costs, expenses, and reasonable fees of professionals covered by this
provision include such charges for the following:

                  9.1 The preparation,  modification,  or renewal of this Credit
Agreement  and  the  Note,  or any  other  documentation  incident  to the  loan
transaction;

                  9.2 Any  litigation,  dispute,  proceeding or action,  whether
instituted by Lender,  Borrower,  or any other  person,  relating to the Note or
this  Agreement,   including   representation   of  Lender  in  any  bankruptcy,
insolvency,  or  reorganization  case or  proceeding  instituted  by or  against
Borrower, and any attempt by Lender to enforce any rights against Borrower;

                  9.3 In the  event  of  bankruptcy  or  insolvency  proceedings
(whether  state or federal)  instituted by or against  Borrower or involving the
Borrower  or  Property  of the  Borrower,  the  Lender  may  recover  all costs,
expenses,  and reasonable  attorney fees incurred to protect or defend  Lender's
rights under the Note,  and other  documents  underlying  the loan  transactions
whether such costs,  expenses,  and attorney fees be  contractual  or bankruptcy
related,  including costs, expenses,  and attorney fees for meetings,  sessions,
matters,  proceedings and litigation involving issues solely distinct to federal
bankruptcy  law,  rules  and  proceedings  as well as other  federal  and  state
litigation and proceedings;

                  9.4  The  inspection,  verification,  protection,  collection,
processing, sale, liquidation, or disposition of security given for the Note;

                  9.5 The preparation  and filing of all reports  required to be
filed by Lender under the Exchange Act during the term of this Credit  Agreement
in connection  with the ownership,  acquisition,  or disposition of the Warrant,
common shares, or other equity securities issued by Borrower.

         10. Maximum Permitted  Interest.  No provision of this Credit Agreement
or any  other  Loan  Document,  or any  transaction  related  thereto,  shall be
construed  or so operate as to require the Borrower to pay interest at a greater
rate than the maximum  allowed by  applicable  state or federal law.  Should any
interest or other charges paid or payable by the Borrower in connection with the
Loan result in the  computation  or earning of interest in excess of the maximum
allowed by  applicable  state or federal law, then any and all such excess shall
be and the same is hereby  waived by Lender,  and any and all such  excess  paid
shall be credited  automatically  against and in  reduction  of the  outstanding
principal  balance due of the Loan, and the portion of said excess which exceeds
such principal balance shall be paid by Lender to the Borrower.

                                        9

<PAGE>

         11.  Governing  Law.  This  Credit  Agreement  shall be  construed  and
governed in all respects by the laws of the State of California.

         12.  Successors and Assigns.  The  provisions of this Credit  Agreement
shall inure to the benefit of, and be binding upon, the  respective  successors,
assigns, heirs, executors and administrators of Borrower and Lender.

         13. Entire  Agreement;  Amendment.  This Credit Agreement and the other
Loan Documents  constitute the full and entire understanding and agreement among
the parties with regard to the subject matter thereof. This Credit Agreement and
any  term of  this  Credit  Agreement  may be  amended,  waived,  discharged  or
terminated only by a written instrument signed by the party to be charged.

         14. Survival.  Borrower's  representations and warranties  contained in
this  Credit   Agreement  shall  survive  the  funding  of  each  Draw  and  any
investigation made by any party until the Maturity Date.

         15. Notices. All notices and other communications required or permitted
to be given pursuant to this  Agreement  shall be in writing and shall be deemed
given four (4) days after being  deposited in the United States mail,  certified
postage  prepaid,  return  receipt  requested,  or when  delivered  by hand,  by
messenger or express air freight service, in any case addressed as follows:

         To Lender:          Alfred D. Kingsley
                             909 Third Avenue, 30th Floor
                             New York, NY 10022
                             FAX:  (212) 350-5253

         To Borrower:        BioTime, Inc.
                             935 Pardee Street
                             Berkeley, California 94710
                             Attention: Paul Segall, Chief Executive Officer
                             FAX:  (510) 845-7914

                             with a copy to:
                             Richard S. Soroko, Esq.
                             Lippenberger, Thompson, Welch, Soroko & Gilbert LLP
                             201 Tamal Vista, Blvd.
                             Corte Madera, California  94925

Any party may change its address  for the  purpose of this  Section 15 by giving
notice to each other party in accordance with this Section 15.

         16. Delays and  Omissions.  No delay or omission to exercise any right,
power,  or remedy  accruing  to Lender,  upon any breach or default of  Borrower
under this Credit  Agreement

                                       10

<PAGE>

or any other Loan  Document,  shall impair any such right,  power,  or remedy of
Lender,  nor shall it be construed to be a waiver of, or an acquiescence in, any
such breach or default or any similar  breach or default  thereafter  occurring;
nor shall any waiver of any  single  breach or default be deemed a waiver of any
other breach or default theretofore or thereafter occurring. Any waiver, permit,
consent,  or  approval  of any kind or  character  on the part of  Lender of any
breach or default by  Borrower  under this  Credit  Agreement  or any other Loan
Document, or any waiver of any provisions or conditions of this Credit Agreement
or any other Loan  Document  by Lender,  must be made in  writing,  and shall be
effective  only to the  extent  specifically  set  forth  in such  writing.  All
remedies  either under this  Agreement or by law and  otherwise  afforded to any
party shall be cumulative and not alternative.

         17. Rules of Construction.

                  17.1  Titles  and  Subtitles.  The titles or  headings  of the
Sections  and  paragraphs  of  this  Credit  Agreement  are for  convenience  of
reference only and are not to be considered in construing this Credit Agreement.

                  17.2 Singular; Plural. Whenever appropriate in this Agreement,
terms in the  singular  form shall  include  the plural (and vice versa) and any
gender form shall include all others.

                  17.3   Section   Headings.   Section   headings  are  for  the
convenience of the parties and do not form a part of this Agreement.

                  17.4  Sections  and  Other  References.   References  in  this
Agreement to sections,  paragraphs,  and  exhibits are  references  to articles,
sections,  and paragraphs in this Agreement and schedules and exhibits  attached
to this Agreement unless specified otherwise.

         18.  Severability.  If one or more provisions of this Credit  Agreement
are held to be  unenforceable  under  applicable  law,  each such  unenforceable
provision  shall be excluded from this Credit  Agreement and the balance of this
Credit  Agreement shall be interpreted as if each such  unenforceable  provision
were so excluded,  and the balance of this Credit  Agreement  as so  interpreted
shall be enforceable in accordance with its terms.

         19.  Counterparts.  This Credit Agreement may be executed in any number
of counterparts,  each of which shall be an original,  but all of which together
shall constitute one instrument.

                                       11

<PAGE>

         IN WITNESS WHEREOF,  the parties hereto have executed this Agreement as
of the date first above written.

BORROWER:                           BIOTIME, INC.

                                    By _________________________________________

                                    Title ______________________________________

                                    By _________________________________________

                                    Title ______________________________________

LENDER:                             ____________________________________________
                                            Alfred D.  Kingsley

                                       12

<PAGE>

                                                                       EXHIBIT A

                              REVOLVING CREDIT NOTE

$300,000                                                          March 27, 2002

         FOR VALUE  RECEIVED,  the  undersigned,  BioTime,  Inc.,  a  California
corporation  (Borrower")  hereby  promises  to pay to the  order  of  Alfred  D.
Kingsley  ("Lender")  the  principal  sum  of  THREE  HUNDRED  THOUSAND  DOLLARS
($300,000) or such lesser amount as may from time to time be  outstanding as the
Loan pursuant to that certain Revolving Line of Credit Agreement,  of even date,
between Borrower and Lender (the "Credit Agreement"),  together with interest on
the unpaid balance of the Loan at the rate or rates  hereinafter set forth. This
Revolving  Credit  Note is the  Note  described  in the  Credit  Agreement.  All
capitalized  terms not  otherwise  defined in this Note shall have the  meanings
defined in the Credit Agreement.

         1. Terms of Payment.

                  (a) Interest Rate. Interest shall accrue and be payable at the
rate of 10% per annum on the outstanding principal balance of the Loan. Interest
shall accrue from the date of each disbursement of principal pursuant to a Draw.
Accrued interest shall be paid with principal.  Interest will be charged on that
part of  outstanding  principal of the Loan which has not been paid and shall be
calculated on the basis of a 360-day year and a 30-day month.

                  (b) Payments of Principal.  The outstanding  principal balance
of the  Loan,  together  with  accrued  interest,  shall  be paid in full on the
Maturity Date. "Maturity Date" means the earlier of (i) March 31, 2003, and (ii)
such date on which Borrower shall have received an aggregate of $600,000 through
(A) the sale of capital stock, (B) the collection of license fees, signing fees,
milestone fees, or similar fees under  Borrower's  Exclusive  License  Agreement
with  Abbott  Laboratories,  or under any  other  present  or  future  agreement
pursuant to which Borrower grants one or more licenses to use Borrower's patents
or technology,  (C) funds borrowed from other lenders, or (D) any combination of
sources under clauses (A) through (C).

                  (c)  Mandatory  Prepayment  of  Principal.  In the event  that
Borrower  receives,  in the aggregate,  an amount of funds in excess of $300,000
but less than  $600,000  from  sources  described  in clauses (A) through (C) of
paragraph  (b) of this  Section  1,  Borrower  shall  use the funds in excess of
$300,000 to prepay principal,  plus accrued  interest,  within two business days
after such funds are  received  by  Borrower,  and the  amount of  principal  so
prepaid  shall not be available  for further  Draws by Borrower  during the Draw
Period.

                  (d)  Optional  Prepayment  of  Principal.  Borrower may prepay
principal,  with  accrued  interest,  at any time and the amount of principal so
prepaid shall be available for further Draws by Borrower  during the Draw Period
to the extent that the prepayment of principal was not required under  paragraph
(c) of this Section 1.

                                       1

<PAGE>

                  (e) Default  Interest  Rate.  In the event that any payment of
principal or interest is not paid within five (5) days from on the date on which
the same is due and payable, such payment shall continue as an obligation of the
Borrower, and interest thereon from the due date of such payment and interest on
the entire  unpaid  balance of the Loan shall  accrue  until paid in full at the
lesser of (i) fifteen percent (15%) per annum, or (ii) the highest interest rate
permitted under applicable law (the "Default Rate"). From and after the Maturity
Date or upon  acceleration of the Note, the entire unpaid  principal  balance of
the Loan with all unpaid interest  accrued  thereon,  and any and all other fees
and charges then due at such maturity, shall bear interest at the Default Rate.

                  (f)  Date of  Payment.  If the  date on  which  a  payment  of
principal  or  interest  on the Loan is due is a day other than a Business  Day,
then payment of such principal or interest need not be made on such date but may
be made on the next succeeding Business Day.

                  (g)  Application  of Payments.  All payments  shall be applied
first to costs of  collection,  next to late charges or other sums owing Lender,
next to accrued  interest,  and then to  principal,  or in such  other  order or
proportion as Lender, in its sole discretion, may determine.

                  (h)  Currency.  All  payments  shall be made in United  States
Dollars.

         2. Events of Default. The following shall constitute Events of Default:
(a) the  default of Borrower in the  payment of any  interest or  principal  due
under this Note or the Credit Agreement;  (b) the failure of Borrower to perform
or observe any other term or  provision  of this Note,  or any term,  provision,
covenant,  or agreement in the Credit Agreement or any other Loan Document;  (c)
any act,  omission,  or other event that constitutes an "Event of Default" under
the Credit Agreement;  (d) any  representation or warranty of Borrower contained
in the Credit  Agreement or in any other Loan  Document,  or in any  certificate
delivered  by  Borrower  pursuant  to the  Credit  Agreement  or any other  Loan
Document, is false or misleading in any material respect when made or given; (e)
Borrower  becoming the subject of any order for relief in a proceeding under any
Debtor Relief Law (as defined below);  (f) Borrower making an assignment for the
benefit of creditors; (g) Borrower applying for or consenting to the appointment
of any receiver, trustee, custodian, conservator, liquidator,  rehabilitator, or
similar officer for it or for all or any part of its property or assets; (h) the
appointment  of  any  receiver,  trustee,  custodian,  conservator,  liquidator,
rehabilitator,  or similar  officer for Borrower,  or for all or any part of the
property or assets of Borrower,  without the application or consent Borrower, if
such  appointment  continues  undischarged  or unstayed for sixty (60)  calendar
days; (i) Borrower  instituting or consenting to any proceeding under any Debtor
Relief  Law with  respect  to  Borrower  or all or any part of its  property  or
assets, or the institution of any similar case or proceeding without the consent
of Borrower,  if such case or proceeding  continues  undismissed or unstayed for
sixty (60) calendar days; (j) the dissolution or liquidation of Borrower, or the
winding-up of the business or affairs of Borrower;  (k) the taking of any action
by Borrower to initiate any of the actions  described in clauses (f) through (j)
of this paragraph;  (l) the issuance or levy of any judgment,  writ,  warrant of
attachment or execution or similar  process  against all or any material part of
the property or assets of Borrower if such process is not  released,  vacated or
fully bonded within sixty (60) calendar days after its issue or levy; or (m) any
breach or default by Borrower under its Exclusive  License Agreement with Abbott
Laboratories,  the  occurrence  of an Event of Default under  Borrower's  Series
2001-A  Debentures,  or any  breach  or  default  by  Borrower  under

                                       2

<PAGE>

any loan agreement, promissory note, or other instrument evidencing indebtedness
payable to a third party.  As used in this Note,  the term  "Debtor  Relief Law"
means the Bankruptcy  Code of the United States of America,  as amended,  or any
other   applicable   liquidation,   conservatorship,   bankruptcy,   moratorium,
rearrangement,  receivership,  insolvency,  reorganization,  or  similar  debtor
relief law affecting the rights of creditors generally.

         3. Remedies On Default.  Upon the occurrence of an Event of Default, at
Lender's  option,  all unpaid  principal  and  accrued  interest,  and all other
amounts payable under this Note shall become immediately due and payable without
presentment,  demand, notice of non-payment,  protest, or notice of non-payment.
Lender also shall have all other rights,  powers,  and remedies  available under
the Credit  Agreement  and any other Loan  Document,  or  accorded  by law or at
equity. All rights,  powers, and remedies of Lender may be exercised at any time
by Lender and from time to time after the occurrence of an Event of Default. All
rights,  powers,  and  remedies of Lender in  connection  with this Note and any
other Loan Document are cumulative and not exclusive and shall be in addition to
any other rights, powers, or remedies provided by law or equity.

         4. Miscellaneous.

                  (a) Borrower  and all  guarantors  and  endorsers of this Note
severally waive (i) presentment,  demand,  protest,  notice of dishonor, and all
other notices; (ii) any release or discharge arising from any extension of time,
discharge of a prior party, release of any or all of the security for this Note,
and (iii) any other cause of release or discharge  other than actual  payment in
full of all indebtedness evidenced by or arising under this Note.

                  (b) No delay or  omission  of Lender to  exercise  any  right,
whether  before or after an Event of  Default,  shall  impair  any such right or
shall be construed to be a waiver of any right or default, and the acceptance of
any past-due amount at any time by the Lender shall not be deemed to be a waiver
of the right to require  prompt  payment  when due of any other  amounts then or
thereafter  due and  payable.  The  Lender  shall not be  deemed,  by any act or
omission,  to have  waived any of Lender's  rights or  remedies  under this Note
unless  such  waiver is in  writing  and  signed by Lender  and then only to the
extent  specifically  set forth in such writing.  A waiver with reference to one
event shall not be construed as continuing or as a bar to or waiver of any right
or remedy as to a subsequent event.

                  (c) Lender may  accept,  indorse,  present  for  payment,  and
negotiate  checks  marked  "payment  in full" or with  words of  similar  effect
without waiving  Lender's right to collect from Borrower the full amount owed by
Borrower.

                  (d) Time is of the essence under this Note.  Upon any Event of
Default,  the Lender may exercise  all rights and remedies  provided for in this
Note and by law,  including,  but not limited to, the right to immediate payment
in full of this Note.

                  (e) The rights and  remedies of the Lender as provided in this
Note,  in the Credit  Agreement and in law or equity,  shall be  cumulative  and
concurrent, and may be pursued singularly, successively, or together at the sole
discretion  of the Lender,  and may be exercised

                                       3

<PAGE>

as often as occasion  therefor shall occur; and the failure to exercise any such
right or remedy  shall in no event be  construed as a waiver or a release of any
such right or remedy.

                  (f) It is expressly agreed that if this Note is referred to an
attorney or if suit is brought to collect this Note or any amount due under this
Note,  or to enforce or protect  any rights  conferred  upon Lender by this Note
then Borrower promises and agrees to pay on demand all costs,  including without
limitation, reasonable attorneys' fees, incurred by Lender in the enforcement of
Lender's rights and remedies under this Note, and such other agreements.

                  (g) The terms,  covenants,  and  conditions  contained in this
Note shall be binding upon the heirs, executors, administrators, successors, and
assigns of  Borrower,  and each of them,  and shall  inure to the benefit of the
heirs, executors, administrators, successors and assigns of Lender.

                  (h) This Note shall be  construed  under and  governed  by the
laws of the State of California without regard to conflicts of law.

                  (i) No provision of this Note shall be construed or so operate
as to require the  Borrower to pay  interest at a greater  rate than the maximum
allowed by applicable state or federal law. Should any interest or other charges
paid or payable by the Borrower in connection  with this Note or the Loan result
in the  computation  or earning of interest in excess of the maximum  allowed by
applicable  state or federal law,  then any and all such excess shall be and the
same is hereby  waived by  Lender,  and any and all such  excess  paid  shall be
credited  automatically  against and in reduction of the  outstanding  principal
balance  due of the Loan,  and the  portion of said excess  which  exceeds  such
principal balance shall be paid by Lender to the Borrower.

BORROWER:                  BIOTIME, INC.

                           By ______________________________________________

                           Title ___________________________________________

                           By ______________________________________________

                           Title ___________________________________________

                                        4

<PAGE>

                                                                       EXHIBIT B

                                 ---------------

                                Warrant Agreement

                           Dated as of March 27, 2002

                                 ---------------

<PAGE>

         WARRANT AGREEMENT, dated as of March 27, 2002, between BioTime, Inc., a
California corporation (the "Company"), and Alfred D. Kingsley (the "Lender").

         The  Company  proposes to issue a Common  Share  Purchase  Warrant,  as
hereinafter described (the "Warrants"), to purchase up to an aggregate of 30,000
of its Common  Shares,  no par value (the "Common  Stock") (the shares of Common
Stock  issuable  upon exercise of the Warrants  being  referred to herein as the
"Warrant Shares"),  in connection with the Revolving Line of Credit Agreement of
even date (the "Credit Agreement"), between the Company and the Lender.

         In  consideration  of the foregoing and for the purpose of defining the
terms and  provisions of the Warrant and the respective  rights and  obligations
thereunder  of the  Company  and  each  registered  owner  of the  Warrant  (the
"Holder"), the Company and the Lender hereby agree as follows:

         SECTION 1. Issuance of Warrants;  Term of Warrants.  Concurrently  with
the  execution  and delivery of this  Agreement  and the Credit  Agreement,  the
Company is issuing and  delivering  to the Lender a Warrant to  purchase  30,000
Warrant  Shares,  which  Warrant  shall  be  represented  by  a  certificate  in
substantially  the  form of  Exhibit  A  hereto.  Subject  to the  terms of this
Agreement,  a Holder of any of such Warrant  (including  any Warrants into which
the Warrant may be divided) shall have the right,  which may be exercised at any
time  prior to 5:00  p.m.,  New York  Time on March 26,  2007  (the  "Expiration
Date"),  to purchase from the Company the number of fully paid and nonassessable
Warrant  Shares  which the Holder may at the time be entitled  to purchase  upon
exercise of any of such Warrant.

         SECTION 2. Transferability and Form of Warrant.

                  2.1  Registration.  The Warrant shall be numbered and shall be
registered on the books of the Company (the "Warrant  Register") as issued.  The
Company  and the  Warrant  Agent (if  appointed)  shall be entitled to treat the
Holder of any Warrant as the owner in fact  thereof for all  purposes  and shall
not be bound to  recognize  any  equitable  or other  claim or  interest in such
Warrant  on the part of any  other  person,  and  shall  not be  liable  for any
registration  of transfer of any Warrant which is registered or to be registered
in the name of a fiduciary  or the  nominee of a fiduciary  unless made with the
actual  knowledge that a fiduciary or nominee is committing a breach of trust in
requesting such  registration or transfer,  or with such knowledge of such facts
that its participation therein amounts to bad faith. The Warrant shall initially
be registered in the name of the Lender.

                  2.2 Restrictions on Exercise and Transfer. The Warrant may not
be exercised, sold, pledged, hypothecated,  transferred or assigned, in whole or
in part,  unless a registration  statement  under the Securities Act of 1933, as
amended (the "Act"), and under any applicable state securities laws is effective
therefor  or,  an  exemption  from  such  registration  is then  available.  Any
exercise, sale, pledge,  hypothecation,  transfer, or assignment in violation of
the  foregoing  restriction  shall be  deemed  null  and void and of no  binding
effect. The Company shall be entitled to obtain, as a condition precedent to its
issuance of any certificates representing Warrant Shares or any other securities
issuable upon any exercise of the Warrant, a letter or other instrument from the
Holder containing such covenants,  representations  or warranties by such Holder
as reasonably

                                       1

<PAGE>

deemed  necessary  by  Company  to effect  compliance  by the  Company  with the
requirements of applicable federal and/or state securities laws.

                  2.3  Transfer.  Subject to Section 2.2,  the Warrant  shall be
transferable only on the Warrant Register upon delivery thereof duly endorsed by
the Holder or by his duly authorized attorney or representative,  or accompanied
by proper  evidence of  succession,  assignment or authority to transfer,  which
endorsement shall be guaranteed by a bank or trust company or a broker or dealer
which is a member of the National Association of Securities Dealers, Inc. In all
cases of transfer by an attorney, the original power of attorney, duly approved,
or a copy  thereof,  duly  certified,  shall be  deposited  and remain  with the
Company (or the Warrant Agent, if appointed).  In case of transfer by executors,
administrators,  guardians or other legal  representatives,  duly  authenticated
evidence  of  their  authority  shall be  produced,  and may be  required  to be
deposited  and remain with the Company (or the Warrant  Agent,  if appointed) in
its discretion. Upon any registration of transfer, the Company shall execute and
deliver (or if appointed, the Warrant Agent shall countersign and deliver) a new
Warrant or Warrants to the persons entitled thereto.

                  2.4  Form  of  Warrant.  The  text of the  Warrant  and of the
Purchase Form shall be  substantially as set forth in Exhibit A attached hereto.
The price per  Warrant  Share and the number of  Warrant  Shares  issuable  upon
exercise of each  Warrant  are  subject to  adjustment  upon the  occurrence  of
certain events, all as hereinafter  provided.  The Warrants shall be executed on
behalf of the Company by its Chairman of the Board, President or one of its Vice
Presidents,  under  its  corporate  seal  reproduced  thereon  attested  by  its
Secretary  or Assistant  Secretary.  The  signature of any such  officers on the
Warrants may be manual or facsimile,  provided,  however,  that the signature of
any  such  officers  must be  manual  until  such  time as a  Warrant  Agent  is
appointed.

                  Warrants  bearing  the  manual  or  facsimile   signatures  of
individuals  who were at any time the proper  officers of the Company shall bind
the Company, notwithstanding that such individuals or any one of them shall have
ceased to hold such offices  prior to the  delivery of such  Warrants or did not
hold such offices on the date of this Agreement.

                  In the event that the Company shall appoint a Warrant Agent to
act on its  behalf  in  connection  with the  division,  transfer,  exchange  or
exercise of  Warrants,  the Warrants  issued after the date of such  appointment
shall be dated as of the date of  countersignature  thereof by the Warrant Agent
upon  division,  exchange,  substitution  or  transfer.  Until  such time as the
Company shall appoint a Warrant Agent, Warrants shall be dated as of the date of
execution  thereof by the Company either upon initial issuance or upon division,
exchange, substitution or transfer.

         SECTION 3.  Countersignature of Warrants. In the event that the Company
shall  appoint  a Warrant  Agent to act on its  behalf  in  connection  with the
division,  transfer, exchange or exercise of Warrants, the Warrants issued after
the date of such appointment shall be countersigned by the Warrant Agent (or any
successor  to the Warrant  Agent then acting as warrant  agent) and shall not be
valid for any purpose unless so  countersigned.  Warrants may be  countersigned,
however,  by the Warrant Agent (or by its successor as warrant agent  hereunder)
and may be  delivered  by the Warrant  Agent,  notwithstanding  that the persons
whose manual or facsimile  signatures  appear thereon as proper  officers of the
Company shall have ceased to be such officers at the time of such

                                        2

<PAGE>

countersignature,  issuance or  delivery.  The Warrant  Agent (if so  appointed)
shall, upon written instructions of the Chairman of the Board, the President, an
Executive  or Senior Vice  President,  the  Treasurer or the  Controller  of the
Company,  countersign,  issue and deliver Warrants entitling the Holders thereof
to purchase not more than 30,000 Warrant Shares (subject to adjustment  pursuant
to Section 10 hereof) and shall  countersign  and deliver  Warrants as otherwise
provided in this Agreement.

         SECTION 4. Exchange of Warrant  Certificates.  Each Warrant certificate
may be  exchanged,  at the option of the Holder  thereof,  for  another  Warrant
certificate or Warrant  certificates  in different  denominations  entitling the
Holder or Holders thereof to purchase a like aggregate  number of Warrant Shares
as the  certificate  or  certificates  surrendered  then  entitle each Holder to
purchase.  Any Holder desiring to exchange a Warrant certificate or certificates
shall make such  request in writing  delivered  to the Company at its  principal
office (or, if a Warrant Agent is appointed,  the Warrant Agent at its principal
office) and shall surrender,  properly endorsed, the certificate or certificates
to be so exchanged. Thereupon, the Company (or, if appointed, the Warrant Agent)
shall  execute  and  deliver  to  the  person  entitled  thereto  a new  Warrant
certificate or certificates,  as the case may be, as so requested,  in such name
or names as such Holder shall designate.

         SECTION 5. Exercise of Warrants; Listing.

                  5.1  Exercise of  Warrants.  A Warrant may be  exercised  upon
surrender  of the  certificate  or  certificates  evidencing  the Warrants to be
exercised, together with the form of election to purchase on the reverse thereof
duly filled in and signed,  which  signature  shall be  guaranteed  by a bank or
trust  company  or a  broker  or  dealer  which  is a  member  of  the  National
Association of Securities Dealers,  Inc., to the Company at its principal office
(or if appointed, the principal office of the Warrant Agent) and upon payment of
the  Warrant  Price  (as  defined  in and  determined  in  accordance  with  the
provisions of Sections 9 and 10 hereof) to the Company (or if appointed,  to the
Warrant Agent for the account of the Company),  for the number of Warrant Shares
in respect of which such Warrants are then  exercised.  Payment of the aggregate
Warrant  Price  (defined  in  Section  9  herein)  shall  be  made in cash or by
certified or bank cashier's check.

                                        3

<PAGE>

                  Subject to Section 6 hereof, upon the surrender of the Warrant
and payment of the Warrant Price as aforesaid, the Company (or if appointed, the
Warrant  Agent)  shall  cause to be issued  and  delivered  with all  reasonable
dispatch to or upon the written order of the Holder and in such name or names as
the Holder may designate,  a certificate or certificates  for the number of full
Warrant  Shares so purchased  upon the exercise of such  Warrant,  together with
cash,  as provided in Section 11 hereof,  in respect of any  fractional  Warrant
Shares otherwise issuable upon such surrender.  Such certificate or certificates
shall be deemed to have been  issued  and any person so  designated  to be named
therein shall be deemed to have become a holder of record of such Warrant Shares
as of the date of the  surrender  of such  Warrants  and  payment of the Warrant
Price, as aforesaid.  The rights of purchase represented by the Warrant shall be
exercisable,  at the election of the Holder thereof, either in full or from time
to time in part and, in the event that a certificate  evidencing  the Warrant is
exercised in respect of less than all of the Warrant Shares  purchasable on such
exercise  at any time  prior to the date of  expiration  of the  Warrant,  a new
certificate  evidencing the  unexercised  portion of the Warrant will be issued,
and the Warrant  Agent (if so  appointed)  is hereby  irrevocably  authorized to
countersign and to deliver the required new Warrant  certificate or certificates
pursuant  to the  provisions  of this  Section  and  Section 3  hereof,  and the
Company, whenever required by the Warrant Agent (if appointed),  will supply the
Warrant Agent with Warrant  certificates  duly executed on behalf of the Company
for such purpose.

                  5.2 Listing of Shares on  Securities  Exchange;  Exchange  Act
Registration.  The  Company  will  promptly  use its best  efforts  to cause the
Warrant  Shares to be listed,  subject to official  notice of  issuance,  on all
national  securities  exchanges  on which the  Common  Stock is listed and whose
rules and regulations  require such listing,  as soon as possible  following the
date hereof.

                  The Company will promptly notify the Holders in the event that
the Company  plans to register the  Warrants  with the  Securities  and Exchange
Commission under the Securities  Exchange Act of 1934, as amended (the "Exchange
Act").

         SECTION 6. Payment of Taxes. The Company will pay all documentary stamp
taxes, if any,  attributable to the initial  issuance of Warrant Shares upon the
exercise of Warrants;  provided, however, that the Company shall not be required
to pay any tax or taxes which may be payable in respect of any transfer involved
in the issue or delivery of any Warrant or certificates  for Warrant Shares in a
name other than that of the registered Holder of such Warrants.

         SECTION  7.  Mutilated  or  Missing  Warrants.   In  case  any  of  the
certificates  evidencing  the  Warrants  shall be  mutilated,  lost,  stolen  or
destroyed,  the  Company  may in its  discretion  issue  and  deliver  (and,  if
appointed,  the Warrant  Agent shall  countersign  and  deliver) in exchange and
substitution for and upon cancellation of the mutilated Warrant certificate,  or
in  lieu of and  substitution  for  the  Warrant  certificate  lost,  stolen  or
destroyed,  a new Warrant  certificate  of like tenor,  but only upon receipt of
evidence  reasonably  satisfactory  to the Company and the Warrant  Agent (if so
appointed) of such loss,  theft or  destruction of such Warrant and an indemnity
or bond, if requested,  also  reasonably  satisfactory to them. An applicant for
such a  substitute  Warrant  certificate  shall  also  comply  with  such  other
reasonable  regulations and pay such other reasonable charges as the Company (or
the Warrant Agent, if so appointed) may prescribe.

                                       4

<PAGE>

         SECTION 8. Reservation of Warrant Shares;  Purchase and Cancellation of
Warrants.

                  8.1 Reservation of Warrant  Shares.  There have been reserved,
and the Company shall at all times keep reserved,  out of its authorized  Common
Stock, a number of shares of Common Stock sufficient to provide for the exercise
of the  rights of  purchase  represented  by the  outstanding  Warrants  and any
additional Warrants issuable hereunder.  The Transfer Agent for the Common Stock
and every  subsequent  transfer  agent for any shares of the  Company's  capital
stock issuable upon the exercise of any of the rights of purchase aforesaid will
be  irrevocably  authorized  and directed at all times to reserve such number of
authorized shares as shall be required for such purpose. The Company will keep a
copy of this  Agreement on file with the Transfer Agent for the Common Stock and
with every  subsequent  transfer  agent for any shares of the Company's  capital
stock  issuable upon the exercise of the rights of purchase  represented  by the
Warrants.  The Warrant Agent,  if appointed,  will be irrevocably  authorized to
requisition  from time to time from such Transfer  Agent the stock  certificates
required to honor outstanding  Warrants upon exercise thereof in accordance with
the terms of this  Agreement.  The Company will supply such Transfer  Agent with
duly executed stock certificates for such purposes and will provide or otherwise
make  available  any cash which may be payable as provided in Section 11 hereof.
The  Company  will  furnish  such  Transfer  Agent  a  copy  of all  notices  of
adjustments  and  certificates  related  thereto,  transmitted  to  each  Holder
pursuant to subsection 10.3 hereof.

                  8.2  Purchase of Warrants by the  Company.  The Company  shall
have the right,  except as limited by law, other agreements or herein,  with the
consent of the Holder,  to purchase or otherwise acquire Warrants at such times,
in such manner and for such consideration as it may deem appropriate.

                  8.3  Cancellation of Warrants.  In the event the Company shall
purchase or otherwise  acquire  Warrants,  the same shall thereupon be cancelled
and  retired.  The  Warrant  Agent (if so  appointed)  shall  cancel any Warrant
surrendered  for  exchange,  substitution,  transfer  or exercise in whole or in
part.

         SECTION 9.  Warrant  Price.  Subject  to any  adjustments  required  by
Section  10  hereof,  the  price  per  share at which  Warrant  Shares  shall be
purchasable  upon  exercise  of a Warrant  (as to any  particular  Warrant,  the
"Warrant Price") shall be Four Dollars ($4.00) per share.

         SECTION 10.  Adjustment of Warrant Price and Number of Warrant  Shares.
The number and kind of securities  purchasable upon the exercise of each Warrant
and the Warrant Price shall be subject to adjustment  from time to time upon the
happening of certain events, as hereinafter defined.

                  10.1  Adjustments.  The number of Warrant  Shares  purchasable
upon the  exercise of each  Warrant  and the  Warrant  Price shall be subject to
adjustment as follows:

                           (a) In the  event  that the  Company  shall (i) pay a
dividend in shares of Common  Stock or make a  distribution  in shares of Common
Stock, (ii) subdivide its outstanding  shares of Common Stock, (iii) combine its
outstanding  shares of Common  Stock  into a smaller  number of shares of Common
Stock or (iv) reclassify or change  (including a change to the right to receive,
or a change  into,  as the case may be (other  than with  respect to a merger or

                                       5

<PAGE>

consolidation  pursuant to the exercise of appraisal  rights),  shares of stock,
other securities,  property,  cash or any combination  thereof) its Common Stock
(including   any  such   reclassification   or  change  in  connection   with  a
consolidation or merger in which the Company is the surviving corporation),  the
number of Warrant Shares  purchasable upon exercise of each Warrant  immediately
prior  thereto  shall be  adjusted so that the Holder of each  Warrant  shall be
entitled to receive the kind and number of Warrant Shares or other securities of
the Company or other property which he would have owned or have been entitled to
receive  after the  happening  of any of the events  described  above,  had such
Warrant been exercised  immediately  prior to the happening of such event or any
record date with respect thereto.  An adjustment made pursuant to this paragraph
(a) shall become  effective  immediately  after the effective date of such event
retroactive to the record date, if any, for such event.

                           (b) In case the Company shall issue  rights,  options
or warrants to all holders of its outstanding  Common Stock,  without any charge
to such holders,  entitling  them to subscribe for or purchase  shares of Common
Stock at a price per share  which is lower at the record  date  mentioned  below
than the then  current  market  price per share of Common  Stock (as  defined in
paragraph (d) below),  the number of Warrant Shares thereafter  purchasable upon
the exercise of each Warrant shall be determined  by  multiplying  the number of
Warrant  Shares  theretofore  pur  chasable  upon  exercise of each Warrant by a
fraction,  of which the numerator  shall be the number of shares of Common Stock
outstanding on the date of issuance of such rights, options or warrants plus the
number of additional shares of Common Stock offered for subscription or purchase
in  connection  with  such  rights,  options  or  warrants,  and  of  which  the
denominator  shall be the number of shares of Common  Stock  outstanding  on the
date of issuance of such rights,  options or warrants  plus the number of shares
which the aggregate offering price of the total number of shares of Common Stock
so offered would  purchase at the current market price per share of Common Stock
at such record date. Such adjustment shall be made whenever such rights, options
or warrants are issued, and shall become effective  immediately after the record
date for the  determination  of  stockholders  entitled to receive  such rights,
options or warrants.

                           (c) In  case  the  Company  shall  distribute  to all
holders of its  shares of Common  Stock,  (including  any  distribution  made in
connection  with a merger in which the  Company is the  surviving  corporation),
evidences  of  its  indebtedness  or  assets   (excluding  cash,   dividends  or
distributions  payable  out of  consolidated  earnings  or  earned  surplus  and
dividends  or  distributions  referred  to in  paragraph  (a)  above) or rights,
options or warrants,  or convertible or exchangeable  securities  containing the
right to  subscribe  for or purchase  shares of Common  Stock  (excluding  those
referred to in  paragraph  (b)  above),  then in each case the number of Warrant
Shares  thereafter  purchasable  upon  the  exercise  of each  Warrant  shall be
determined by multiplying the number of Warrant Shares  theretofore  purchasable
upon the exercise of each Warrant by a fraction, of which the numerator shall be
the then current market price per share of Common Stock (as defined in paragraph
(d) below) on the date of such distribution,  and of which the denominator shall
be the then current  market price per share of Common Stock,  less the then fair
value (as determined by the Board of Directors of the Company or, in the case of
Warrants held by the Lender,  an  independent  investment  banker which shall be
mutually agreeable to the parties,  whose determination,  in each case, shall be
conclusive)  of the  portion  of the  assets or  evidences  of  indebtedness  so
distributed  or of such  subscription  rights,  options or warrants,  or of such
convertible or exchangeable  securities applicable to one share of Common Stock.
Such

                                       6

<PAGE>

adjustment  shall be made  whenever  any such  distribution  is made,  and shall
become effective on the date of distribution  retroactive to the record date for
the determination of shareholders entitled to receive such distribution.

                           (d)  For  the  purpose  of  any   computation   under
paragraphs  (b) and (c) of this Section,  the current  market price per share of
Common  Stock at any date shall be the average of the daily last sale prices for
the 20 consecutive trading days ending one trading day prior to the date of such
computation.  The closing  price for each day shall be the last  reported  sales
price regular way or, in case no such reported sale takes place on such day, the
average of the  closing bid and asked  prices  regular way for such day, in each
case on the principal national securities exchange on which the shares of Common
Stock are listed or  admitted  to trading  or, if not so listed or  admitted  to
trading,  the last sale price of the Common  Stock on the Nasdaq Stock Market or
any comparable system. If the current market price of the Common Stock cannot be
so determined,  the Board of Directors of the Company shall reasonably determine
the current market price on the basis of such quotations as are available.

                           (e) No  adjustment  in the number of  Warrant  Shares
purchasable  hereunder shall be required unless such adjustment would require an
increase  or  decrease  of at least one  percent  (1%) in the  number of Warrant
Shares purchasable upon the exercise of each Warrant;  provided,  however,  that
any  adjustments  which by reason of this  paragraph  (e) are not required to be
made  shall  be  carried  forward  and  taken  into  account  in any  subsequent
adjustment. All calculations shall be made with respect to the number of Warrant
Shares purchasable  hereunder,  to the nearest tenth of a share and with respect
to the Warrant Price payable hereunder, to the nearest whole cent.

                           (f) Whenever the number of Warrant Shares purchasable
upon the exercise of each Warrant is adjusted,  as herein provided,  the Warrant
Price  payable upon  exercise of each Warrant  shall be adjusted by  multiplying
such Warrant Price immediately prior to such adjustment by a fraction,  of which
the  numerator  shall be the  number  of  Warrant  Shares  purchasable  upon the
exercise of each Warrant immediately prior to such adjustment,  and of which the
denominator  shall be the  number  of  Warrant  Shares  purchasable  immediately
thereafter.

                           (g) No  adjustment  in the number of  Warrant  Shares
purchasable  upon the exercise of each Warrant need be made under paragraphs (b)
and (c) if the Company  issues or  distributes  to each  Holder of Warrants  the
rights  options,   warrants,  or  convertible  or  exchangeable  securities,  or
evidences of indebtedness or assets referred to in those  paragraphs  which each
Holder of Warrants  would have been  entitled to receive had the  Warrants  been
exercised  prior to the  happening of such event or the record date with respect
thereto. No adjustment need be made for a change in the par value of the Warrant
Shares.

                           (h) For the purpose of this subsection 10.1, the term
"shares of Common  Stock"  shall mean (i) the class of stock  designated  as the
Common  Stock of the  Company at the date of this  Agreement,  or (ii) any other
class of stock resulting from successive  changes or  reclassifications  of such
shares  consisting  solely of changes in par value,  or from par value to no par
value,  or from no par value to par value.  In the event that at any time,  as a
result of an adjustment made pursuant to paragraph (a) above,  the Holders shall
become  entitled to purchase any  securities of the Company other than shares of
Common Stock,  thereafter  the number of such

                                       7

<PAGE>

other shares so purchasable  upon exercise of each Warrant and the Warrant Price
of such shares shall be subject to adjustment  from time to time in a manner and
on terms as nearly  equivalent as practicable to the provisions  with respect to
the Warrant Shares contained in paragraphs (a) through (i),  inclusive,  and the
provisions  of Section 5 and  subsections  10.2 through  10.5,  inclusive,  with
respect  to the  Warrant  Shares,  shall  apply on like  terms to any such other
securities.

                           (i)  Upon  the  expiration  of any  rights,  options,
warrants or  conversion  or exchange  privileges,  if any thereof shall not have
been exercised,  the Warrant Price and the number of Warrant Shares  purchasable
upon the exercise of each Warrant shall, upon such expiration, be readjusted and
shall  thereafter be such as it would have been had it been originally  adjusted
(or had the original adjustment not been required, as the case may be) as if (A)
the only shares of Common  Stock so issued were the shares of Common  Stock,  if
any, actually issued or sold upon the exercise of such rights, options, warrants
or  conversion or exchange  rights and (B) such shares of Common Stock,  if any,
were issued or sold for the consideration  actually received by the Company upon
such exercise plus the aggregate consideration, if any, actually received by the
Company for the issuance, sale or grant of all such rights, options, warrants or
conversion or exchange rights whether or not exercised.

                  10.2 Voluntary  Adjustment by the Company.  The Company may at
its option, at any time during the term of the Warrants, reduce the then current
Warrant Price to any amount deemed  appropriate by the Board of Directors of the
Company.

                  10.3  Notice of  Adjustment.  Whenever  the  number of Warrant
Shares  purchasable  upon the exercise of each  Warrant or the Warrant  Price of
such Warrant Shares is adjusted,  as herein  provided,  the Company shall, or in
the event that a Warrant Agent is appointed, the Company shall cause the Warrant
Agent promptly to, mail by first class,  postage prepaid,  to each Holder notice
of such  adjustment  or  adjustments.  Such notice shall set forth the number of
Warrant  Shares  purchasable  upon the  exercise of each Warrant and the Warrant
Price of such  Warrant  Shares  after  such  adjustment,  setting  forth a brief
statement  of  the  facts  requiring  such  adjustment  and  setting  forth  the
computation by which such adjustment was made.

                  10.4 No  Adjustment  for  Dividends.  Except  as  provided  in
subsection  10.1, no adjustment in respect of any dividends shall be made during
the term of a Warrant or upon the exercise of a Warrant.

                  10.5    Preservation   of   Purchase   Rights   Upon   Merger,
Consolidation,  etc. In case of any  consolidation of the Company with or merger
of the Company  into  another  corporation  or in case of any sale,  transfer or
lease to another  corporation  of all or  substantially  all the property of the
Company,  the Company or such successor or purchasing  corporation,  as the case
may be,  shall  execute  an  agreement  that each  Holder  shall  have the right
thereafter,  upon such Holder's election, either (i) upon payment of the Warrant
Price in effect  immediately  prior to such action, to purchase upon exercise of
each  Warrant the kind and amount of shares and other  securities  and  property
(including  cash)  which he would  have owned or have been  entitled  to receive
after the happening of such consolidation,  merger,  sale, transfer or lease had
such Warrant been  exercised  immediately  prior to such action (such shares and
other  securities and property  (including  cash) being referred to as the "Sale
Consideration") or (ii) to receive, in cancellation of such Warrant

                                       8

<PAGE>

(and in lieu of paying the Warrant price and exercising such Warrant),  the Sale
Consideration  less a portion  thereof having a fair market value (as reasonably
determined by the Company) equal to the Warrant Price (it being understood that,
if the Sale  Consideration  consists  of more  than one  type of  shares,  other
securities or property,  the amount of each type of shares,  other securities or
property to be received shall be reduced  proportionately);  provided,  however,
that no adjustment in respect of dividends,  interest or other income on or from
such shares or other  securities and property shall be made during the term of a
Warrant or upon the exercise of a Warrant. The Company shall mail by first class
mail,  postage  prepaid,  to each  Holder,  notice of the  execution of any such
agreement.  Such  agreement  shall  provide for  adjustments,  which shall be as
nearly equivalent as may be practicable to the adjustments  provided for in this
Section 10. The  provisions of this  subsection  10.5 shall  similarly  apply to
successive  consolidations,  mergers,  sales,  transfers or leases.  The Warrant
Agent (if appointed) shall be under no duty or  responsibility  to determine the
correctness  of any provisions  contained in any such agreement  relating to the
kind or amount of shares of stock or other  securities  or  property  receivable
upon  exercise of Warrants or with  respect to the method  employed and provided
therein for any  adjustments  and shall be entitled to rely upon the  provisions
contained in any such agreement.

                  10.6 Statement on Warrants. Irrespective of any adjustments in
the Warrant Price or the number or kind of shares  purchasable upon the exercise
of the Warrants, Warrants issued before or after such adjustment may continue to
express  the same  price and  number  and kind of  shares  as are  stated in the
Warrants initially issuable pursuant to this Agreement.

         SECTION 11. Fractional Interests.  The Company shall not be required to
issue  fractional  Warrant Shares on the exercise of Warrants.  If more than one
Warrant  shall be  presented  for  exercise in full at the same time by the same
Holder,  the number of full  Warrant  Shares  which shall be  issuable  upon the
exercise  thereof  shall be  computed  on the basis of the  aggregate  number of
Warrant  Shares  purchasable  on exercise of the Warrants so  presented.  If any
fraction of a Warrant Share would, except for the provisions of this Section 11,
be issuable on the exercise of any Warrant (or specified portion  thereof),  the
Company  shall pay an amount in cash equal to the  average of the daily  closing
sale prices (determined in accordance with paragraph (d) of subsection 10.1) per
share of Common Stock for the 20 consecutive trading days ending one trading day
prior to the date the Warrant is  presented  for  exercise,  multiplied  by such
fraction.

         SECTION  12. No Rights as  Shareholders;  Notices to  Holders.  Nothing
contained  in this  Agreement  or in any of the  Warrants  shall be construed as
conferring upon the Holders or their transferees the right to vote or to receive
dividends or to consent or to receive notice as  shareholders  in respect of any
meeting of  shareholders  for the  election of  directors  of the Company or any
other matter,  or any rights  whatsoever  as  shareholders  of the Company.  If,
however,  at any time prior to the expiration of the Warrants and prior to their
exercise, any of the following events shall occur:

                  (a) the  Company  shall  declare any  dividend  payable in any
securities upon its shares of Common Stock or make any distribution  (other than
a regular cash dividend, as such dividend may be increased from time to time, or
a dividend  payable in shares of Common  Stock) to the  holders of its shares of
Common Stock; or

                                       9

<PAGE>

                  (b) the  Company  shall  offer to the holders of its shares of
Common Stock on a pro rata basis any cash,  additional shares of Common Stock or
other  securities  of the Company or any right to subscribe  for or purchase any
thereof; or

                  (c) a  dissolution,  liquidation  or winding up of the Company
(other than in connection with a consolidation,  merger, sale, transfer or lease
of all  or  substantially  all  of its  property,  assets,  and  business  as an
entirety) shall be proposed,

then in any one or more of said  events  the  Company  shall (a) give  notice in
writing of such event as provided  in Section 14 hereof and (b) if the  Warrants
have been  registered  pursuant  to the Act,  cause  notice of such  event to be
published once in The Wall Street  Journal  (national  edition),  such giving of
notice and  publication to be completed at least 10 days prior to the date fixed
as a record date or the date of closing the transfer books for the determination
of the  stockholders  entitled to such dividend,  distribution,  or subscription
rights  or for  the  determination  of  stockholders  entitled  to  vote on such
proposed  dissolution,  liquidation  or winding up or the date of  expiration of
such offer.  Such notice  shall  specify such record date or the date of closing
the transfer  books or the date of  expiration,  as the case may be.  Failure to
publish, mail or receive such notice or any defect therein or in the publication
or mailing  thereof  shall not affect the  validity of any action in  connection
with such  dividend,  distribution  or  subscription  rights,  or such  proposed
dissolution, liquidation or winding up, or such offer.

         SECTION 13.  Appointment of Warrant Agent.  At such time as the Company
shall register Warrants under the Act, the Company shall appoint a Warrant Agent
to act on behalf of the  Company  in  connection  with the  issuance,  division,
transfer  and  exercise  of  Warrants.  At such time as the  Company  appoints a
Warrant  Agent,  the Company shall enter into a new Warrant  Agreement  with the
Warrant  Agent   pursuant  to  which  all  new  Warrants  will  be  issued  upon
registration of transfer or division,  which will reflect the appointment of the
Warrant Agent, as well as additional customary provisions as shall be reasonably
requested by the Warrant Agent in connection with the performance of its duties.
In the event that a Warrant Agent is  appointed,  the Company shall (i) promptly
notify the Holders of such  appointment  and the place  designated for transfer,
exchange and exercise of the Warrants, and (ii) take such steps as are necessary
to insure that Warrants  issued prior to such  appointment  may be exchanged for
Warrants countersigned by the Warrant Agent.

         SECTION 14.  Notices;  Principal  Office.  Any notice  pursuant to this
Agreement  by  the  Company  or by  any  Holder  to  the  Warrant  Agent  (if so
appointed),  or by the Warrant  Agent (if so  appointed) or by any Holder to the
Company,  shall be in writing and shall be delivered in person,  or mailed first
class, postage prepaid (a) to the Company, at its office,  Attention:  President
or (b) to the  Warrant  Agent,  at its  offices  as  designated  at the time the
Warrant Agent is appointed.  The address of the principal  office of the Company
is 935 Pardee Street,  Berkeley,  California  94710.  Each party hereto may from
time to time change the address to which  notices to it are to be  delivered  or
mailed hereunder by notice to the other party.

                  Any notice mailed pursuant to this Agreement by the Company or
the Warrant  Agent to the Holders  shall be in writing and shall be mailed first
class,  postage  prepaid,  or  otherwise  delivered,  to such  Holders  at their
respective  addresses on the books of the Company or the Warrant  Agent,  as the
case may be.

                                       10

<PAGE>

         SECTION 15.  Successors.  Except as  expressly  provided  herein to the
contrary,  all the  covenants  and  provisions  of this  Agreement by or for the
benefit of the  Company  and the Lender  shall bind and inure to the  benefit of
their respective successors and permitted assigns hereunder.

         SECTION 16. Merger or  Consolidation  of the Company.  The Company will
not  merge or  consolidate  with or  into,  or sell,  transfer  or lease  all or
substantially all of its property to, any other corporation unless the successor
or  purchasing  corporation,  as the  case  may be (if not the  Company),  shall
expressly assume, by supplemental  agreement,  the due and punctual  performance
and  observance of each and every covenant and condition of this Agreement to be
performed and observed by the Company.

         SECTION 17. Investment Representations.  Lender represents and warrants
to BioTime that:

                  17.1 Lender has received the  Company's  financial  statements
for the year ended on December  31,  2001,  as will be included in its Form 10-K
for such fiscal year,  its annual  report on Form 10-K for the fiscal year ended
December 31, 2000, and quarterly  report on Form 10-Q for the fiscal quarter and
nine months ended  September 30, 2001 (the  "Disclosure  Documents").  Lender is
relying on the  information  provided in the  Disclosure  Documents or otherwise
communicated  to Lender in writing by the Company.  Lender has not relied on any
statement or representations inconsistent with those contained in the Disclosure
Documents.  Lender has had a  reasonable  opportunity  to ask  questions  of and
receive answers from the executive officers and directors of the Company, or one
or more  of its  officers,  concerning  the  Company  and to  obtain  additional
information,  to the extent possessed or obtainable without  unreasonable effort
or expense, necessary to verify the information in the Disclosure Documents. All
such questions have been answered to Lender's satisfaction;

                  17.2  Lender  understands  that the  Warrant  and the  Warrant
Shares  are  being  offered  and  sold  without  registration  under  the Act or
qualification  under the California  Corporate  Securities Law of 1968, or under
the laws of other states, in reliance upon the exemptions from such registration
and qualification requirements for non-public offerings. Lender acknowledges and
understands  that the availability of the aforesaid  exemptions  depends in part
upon the accuracy of certain of the representations, declarations and warranties
contained  herein,  which  Lender  hereby makes with the intent that they may be
relied  upon by the  Company  and its  officers  and  directors  in  determining
Lender's suitability to acquire the Warrant. Lender understands and acknowledges
that no federal,  state or other agency has reviewed or endorsed the offering of
the Warrant or the Warrant Shares or made any finding or determination as to the
fairness of the offering or  completeness  of the  information in the Disclosure
Documents;

                  17.3  Lender  understands  that the  Warrant  and the  Warrant
Shares may not be offered,  sold, or transferred in any manner,  and the Warrant
may not be exercised,  unless  subsequently  registered under the Act, or unless
there is an exemption from such  registration  available for such offer, sale or
transfer;

                  17.4 Lender has such knowledge and experience in financial and
business  matters to enable Lender to utilize the  information  contained in the
Disclosure  Documents,  or  otherwise  made  available to Lender to evaluate the
merits and risks of an investment  in the

                                       11

<PAGE>

Warrant and the Warrant Shares and to make an informed  investment decision with
respect thereto.

                  17.5 Lender is acquiring  the Warrant  solely for Lender's own
account and for long-term  investment  purposes,  and not with a view to, or for
sale in connection with, any distribution of the Warrant or Warrant Shares; and

                  17.6  Lender  is an  "accredited  investor,"  as such  term is
defined in Regulation D promulgated under the Act.

         SECTION 18. Registration Rights.

                  18.1 The Company agrees, at its expense,  upon written request
from the Lender,  to register  under the Act, the Warrant and the Warrant Shares
and to take such other  actions as may be necessary to allow the Warrant and the
Warrant Shares to be freely tradable,  without restrictions,  in compliance with
all regulatory  requirements.  A written request for registration  shall specify
the quantity of the Warrant Shares intended to be sold, the plan of distribution
and the identity of the sellers,  which may include the Lender and  assignees of
its rights hereunder  (collectively,  "Selling Securities Holders"), and whether
the  registration  shall be pursuant  to an  underwritten  public  offering or a
"shelf'  registration  pursuant to Rule 415 (or similar rule that may be adopted
by the Securities and Exchange  Commission).  The Company shall not be obligated
to file more than two such  registration  statements,  other  than  registration
statements  on Form S-3.  The Company  shall keep such  registration  statements
effective  for a period  of at  least  nine  months,  except  that  registration
statements  on Form S-3 shall be kept  effective  for at least  three years ( or
such  lesser  period  as the  parties  may  agree,  but in no event  beyond  the
completion of the  distribution or distributions  being made pursuant  thereto).
The Company  shall  utilize Form S-3 if it  qualifies  for such use. The Company
shall make all filings required with respect to the registration  statements and
will use its best efforts to cause such filings to become effective, so that the
Warrant and Warrant Shares being registered shall be registered or qualified for
sale under the  securities  or blue sky laws of such  jurisdictions  as shall be
reasonably  appropriate  for  distribution  of the Warrant  and  Warrant  Shares
covered by the registration  statement.  The Company will furnish to the Selling
Securities  Holders  such  numbers  of  copies  of  a  prospectus,  including  a
preliminary prospectus,  in conformity with the requirements of the Act and such
other related documents as the Selling Securities Holders may reasonably request
in order to effect the sale of the  Warrant and  Warrant  Shares.  To effect any
offering  pursuant to a registration  statement under this Section,  the Company
shall  enter  into  an  agreement  containing   customary   representations  and
warranties, and indemnification and contribution provisions, all for the benefit
of  Selling  Securities  Holders,  and,  in the case of an  Underwritten  public
offering. an underwriting  agreement with an investment banking firm selected by
the Lender and reasonably  acceptable to the Company,  containing such customary
representations and warranties, and indemnification and contribution provisions

                  18.2 If, at any time, the Company  proposes to register any of
its securities  under the Act (otherwise  than pursuant to Section 18.1 above or
on a Form S-8 if such form  cannot be used for  registration  of the  Warrant or
Warrant  Shares  pursuant  to its  terms),  the  Company  shall,  as promptly as
practicable,  give written  notice to the Lender.  The Company  shall include in
such  registration  statement the Warrant and any Warrant Shares  proposed to be
sold by the Selling

                                       12

<PAGE>

Securities  Holders.  Notwithstanding  the  foregoing,  if the  offering  of the
Company's securities is to be made through  underwriters,  the Company shall not
be required to include the Warrant and Warrant  Shares if and to the extent that
the managing  underwriter  reasonably believes in good faith that such inclusion
would materially  adversely  affect such offering unless the Selling  Securities
Holders agree to postpone  their sales until 10 days after the  distribution  is
completed.

                  18.3  The  Company  shall  pay the  cost  of the  registration
statements filed pursuant to this Agreement,  including  without  limitation all
registration and filing fees, fees and expenses of compliance with securities or
blue sky laws (including  counsel's fees and expenses in connection  therewith),
printing  expenses,  messenger and delivery  expenses,  internal expenses of the
Company,  listing  fees and  expenses,  and fees and  expenses of the  Company's
counsel,  independent  accountants and other persons retained or employed by the
Company.  Selling  Securities  Holders  shall  pay  any  underwriters  discounts
applicable to the Warrant and Warrant Shares.

         SECTION 19. Legends. The Warrants and Warrant Shares issued pursuant to
this Agreement shall bear an appropriate  legend,  conspicuously  disclosing the
restrictions  on exercise and transfer under Section 2.2 of this Agreement until
the same are registered for sale under the Act. The Company agrees that upon the
sale of the Warrant and Warrant Shares  pursuant to a registration  statement or
an exemption, upon the presentation of the certificates containing such a legend
to it's transfer agent,  it will remove such legend.  The Company further agrees
to remove the legend at such time as registration  under the Act shall no longer
be required.

         SECTION 20.  Applicable  Law. This  Agreement  and each Warrant  issued
hereunder  shall be governed by and construed in accordance with the laws of the
State of California, without giving effect to principles of conflict of laws.

         SECTION 21. Benefits of this Agreement. Nothing in this Agreement shall
be construed to give to any person or  corporation  other than the Company,  the
Warrant  Agent (if  appointed)  and the  Holders any legal or  equitable  right,
remedy or claim under this  Agreement;  but this Agreement shall be for the sole
and exclusive  benefit of the Company,  the Warrant Agent and the Holders of the
Warrants.

         SECTION 22. Counterparts.  This Agreement may be executed in any number
of counterparts and each of such  counterparts  shall for all purposes be deemed
to be an original,  and all such counterparts shall together  constitute but one
and the same instrument.

         SECTION 23.  Captions.  The captions of the Sections and subsections of
this  Agreement  have been  inserted  for  convenience  only and  shall  have no
substantive effect.

         IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
duly executed, all as of the day and year first above written.

                                            BIOTIME, INC.

                                            By:

                                       13

<PAGE>

                                               Name: Paul Segall, Ph.D

                                               Title: Chairman and Chief
                                                      Executive Officer

Attest:

By:
   Name: Judith Segall
   Title: Secretary

                                            ____________________________________
                                                       Alfred D. Kingsley

                                       14

<PAGE>

                                                                       EXHIBIT A

         THIS WARRANT HAS NOT BEEN REGISTERED  UNDER THE SECURITIES ACT OF 1933,
AS AMENDED,  OR UNDER  APPLICABLE STATE SECURITIES LAWS. THIS WARRANT MAY NOT BE
EXERCISED, SOLD, PLEDGED, HYPOTHECATED,  TRANSFERRED OR ASSIGNED EXCEPT UNDER AN
EFFECTIVE  REGISTRATION STATEMENT UNDER SUCH ACT AND APPLICABLE STATE SECURITIES
LAWS, UNLESS AN EXEMPTION FROM SUCH REGISTRATION IS AVAILABLE.

               VOID AFTER 5:00 P.M. NEW YORK TIME, March 26, 2007

Certificate No. ______                                       Warrant to Purchase
                                                       [Insert number of Shares]
                                                          Shares of Common Stock

                                  BIOTIME, INC.
                         COMMON SHARE PURCHASE WARRANTS

         This  certifies  that, for value  received,  [Insert name of Holder] or
registered assigns (the "Holder"),  is entitled to purchase from BioTime, Inc. a
California  corporation (the  "Company"),  at a purchase price per share [Insert
Warrant Price determined pursuant to Sections 9 and 10 of the Warrant Agreement]
(the "Warrant  Price"),  the number of its Common Shares, no par value per share
(the  "Common  Stock"),  shown  above.  The  number of shares  purchasable  upon
exercise of the Common Share Purchase  Warrants (the "Warrants") and the Warrant
Price are  subject to  adjustment  from time to time as set forth in the Warrant
Agreement  referred to below.  Outstanding  Warrants not exercised prior to 5:00
p.m., New York time, on March 26, 2007 shall thereafter be void.

         Subject to restriction specified in the Warrant Agreement, Warrants may
be exercised  in whole or in part by  presentation  of this Warrant  Certificate
with the Purchase Form on the reverse side hereof duly executed, which signature
shall be  guaranteed by a bank or trust company or a broker or dealer which is a
member of the National Association of Securities Dealers, Inc., and simultaneous
payment of the Warrant  Price (or as otherwise set forth in Section 10.5) of the
Warrant  Agreement at the principal office of the Company (or if a Warrant Agent
is appointed,  at the principal  office of the Warrant  Agent).  Payment of such
price shall be made in cash or by certified or bank cashier's check. As provided
in the Warrant  Agreement,  the  Warrant  Price and the number or kind of shares
which may be  purchased  upon the  exercise  of the  Warrant  evidenced  by this
Warrant  Certificate  are,  upon the  happening  of certain  events,  subject to
modification and adjustment.

         This  Warrant  Certificate  is issued  under and in  accordance  with a
Warrant  Agreement  dated as of March 27, 2002 between the Company and Alfred D.
Kingsley  and is subject to the terms and  provisions  contained  in the Warrant
Agreement,  to all of which the Holder of this

                                       15

<PAGE>

Warrant Certificate by acceptance of this Warrant Certificate  consents.  A copy
of the  Warrant  Agreement  may be obtained  by the Holder  hereof upon  written
request to the Company.  In the event that pursuant to Section 13 of the Warrant
Agreement a Warrant Agent is appointed and a new warrant  agreement entered into
between the  Company and such  Warrant  Agent,  then such new warrant  agreement
shall  constitute  the Warrant  Agreement  for purposes  hereof and this Warrant
Certificate  shall be deemed to have been  issued  pursuant  to such new warrant
agreement.

         Upon any  partial  exercise of the Warrant  evidenced  by this  Warrant
Certificate,  there  shall  be  issued  to  the  Holder  hereof  a  new  Warrant
Certificate  in respect of the  shares of Common  Stock as to which the  Warrant
evidenced  by this  Warrant  Certificate  shall  not have been  exercised.  This
Warrant  Certificate  may be  exchanged  at the  office of the  Company  (or the
Warrant Agent, if appointed) by surrender of this Warrant  Certificate  properly
endorsed  either  separately  or in  combination  with one or more other Warrant
Certificates  for one or more new Warrant  Certificates  evidencing the right of
the  Holder  thereof  to  purchase  the  aggregate  number  of  shares  as  were
purchasable on exercise of the Warrants evidenced by the Warrant  Certificate or
Certificates exchanged. No fractional shares will be issued upon the exercise of
any  Warrant,  but the Company  will pay the cash value  thereof  determined  as
provided in the Warrant Agreement.  This Warrant  Certificate is transferable at
the office of the Company (or the Warrant Agent, if appointed) in the manner and
subject to the limitations set forth in the Warrant Agreement.

         The Holder hereof may be treated by the Company,  the Warrant Agent (if
appointed)  and all other persons  dealing with this Warrant  Certificate as the
absolute owner hereof for any purpose and as the person entitled to exercise the
rights  represented  hereby,  or to the  transfer  hereof  on the  books  of the
Company, any notice to the contrary notwithstanding,  and until such transfer on
such books,  the Company (and the Warrant  Agent,  if  appointed)  may treat the
Holder hereof as the owner for all purposes.

         Neither the Warrant nor this Warrant Certificate entitles any Holder to
any of the rights of a stockholder of the Company.

         [This  Warrant  Certificate  shall not be valid or  obligatory  for any
purpose until it shall have been countersigned by the Warrant Agent.]*

                                       16

<PAGE>

DATED:

                                                     BIOTIME, INC.

(Seal)                                               By:________________________

                                                     Title:

Attest:____________________

[COUNTERSIGNED:

                                    ,
WARRANT AGENT

By: _________________________________]*
         Authorized Signature

--------------------
*        To be part of the Warrant only after the appointment of a Warrant Agent
         pursuant to Section 13 of the Warrant Agreement.

                                       17

<PAGE>

                                  PURCHASE FORM

                    (To be executed upon exercise of Warrant)

To BioTime, Inc.:

         The  undersigned  hereby  irrevocably  elects to exercise  the right of
purchase  represented  by the within  Warrant  Certificate  for, and to purchase
thereunder,  _____ shares of Common Stock, as provided for therein,  and tenders
herewith  payment  of the  purchase  price  in  full  in the  form  of cash or a
certified or bank cashier's check in the amount of $_________.

         Please issue a certificate  or  certificates  for such shares of Common
Stock in the name of, and pay any cash for any fractional share to:

PLEASE INSERT SOCIAL SECURITY                 NAME
OR OTHER IDENTIFYING NUMBER                        (Please Print Name &
OF ASSIGNEE                                          Address)

___________________________                   Address

___________________________                   Signature

                                                   NOTE: The   above   signature
                                                         should       correspond
                                                         exactly  with  the name
                                                         on  the  face  of  this
                                                         Warrant  Certificate or
                                                         with  the  name  of the
                                                         assignee  appearing  in
                                                         the   assignment   form
                                                         below.

And, if said number of shares shall not be all the shares  purchasable under the
within  Warrant  Certificate,  a new Warrant  Certificate is to be issued in the
name of said  undersigned  for the balance  remaining  of the share  purchasable
thereunder less any fraction of a share paid in cash.

                                       18

<PAGE>

                                   ASSIGNMENT

          (To be executed only upon assignment of Warrant Certificate)

         For value received,  _____________  hereby sells, assigns and transfers
unto  _______________ the within Warrant  Certificate,  together with all right,
title and interest therein,  and does hereby irrevocably  constitute and appoint
_________________ attorney, to transfer said Warrant Certificate on the books of
the within-named Company, with full power of substitution in the premises.

Dated:___________________                       ________________________________
                                                NOTE: The above signature should
                                                      correspond   exactly  with
                                                      the  name  on the  face of
                                                      this Warrant Certificate.

                                       19---------------

                                Warrant Agreement

                           Dated as of March 27, 2002

                                 ---------------

<PAGE>

         WARRANT AGREEMENT, dated as of March 27, 2002, between BioTime, Inc., a
California corporation (the "Company"), and Alfred D. Kingsley (the "Lender").

         The  Company  proposes to issue a Common  Share  Purchase  Warrant,  as
hereinafter described (the "Warrants"), to purchase up to an aggregate of 30,000
of its Common  Shares,  no par value (the "Common  Stock") (the shares of Common
Stock  issuable  upon exercise of the Warrants  being  referred to herein as the
"Warrant Shares"),  in connection with the Revolving Line of Credit Agreement of
even date (the "Credit Agreement"), between the Company and the Lender.

         In  consideration  of the foregoing and for the purpose of defining the
terms and  provisions of the Warrant and the respective  rights and  obligations
thereunder  of the  Company  and  each  registered  owner  of the  Warrant  (the
"Holder"), the Company and the Lender hereby agree as follows:

         SECTION 1. Issuance of Warrants;  Term of Warrants.  Concurrently  with
the  execution  and delivery of this  Agreement  and the Credit  Agreement,  the
Company is issuing and  delivering  to the Lender a Warrant to  purchase  30,000
Warrant  Shares,  which  Warrant  shall  be  represented  by  a  certificate  in
substantially  the  form of  Exhibit  A  hereto.  Subject  to the  terms of this
Agreement,  a Holder of any of such Warrant  (including  any Warrants into which
the Warrant may be divided) shall have the right,  which may be exercised at any
time  prior to 5:00  p.m.,  New York  Time on March 26,  2007  (the  "Expiration
Date"),  to purchase from the Company the number of fully paid and nonassessable
Warrant  Shares  which the Holder may at the time be entitled  to purchase  upon
exercise of any of such Warrant.

         SECTION 2. Transferability and Form of Warrant.

                  2.1  Registration.  The Warrant shall be numbered and shall be
registered on the books of the Company (the "Warrant  Register") as issued.  The
Company  and the  Warrant  Agent (if  appointed)  shall be entitled to treat the
Holder of any Warrant as the owner in fact  thereof for all  purposes  and shall
not be bound to  recognize  any  equitable  or other  claim or  interest in such
Warrant  on the part of any  other  person,  and  shall  not be  liable  for any
registration  of transfer of any Warrant which is registered or to be registered
in the name of a fiduciary  or the  nominee of a fiduciary  unless made with the
actual  knowledge that a fiduciary or nominee is committing a breach of trust in
requesting such  registration or transfer,  or with such knowledge of such facts
that its participation therein amounts to bad faith. The Warrant shall initially
be registered in the name of the Lender.

                  2.2 Restrictions on Exercise and Transfer. The Warrant may not
be exercised, sold, pledged, hypothecated,  transferred or assigned, in whole or
in part,  unless a registration  statement  under the Securities Act of 1933, as
amended (the "Act"), and under any applicable state securities laws is effective
therefor  or,  an  exemption  from  such  registration  is then  available.  Any
exercise, sale, pledge,  hypothecation,  transfer, or assignment in violation of
the  foregoing  restriction  shall be  deemed  null  and void and of no  binding
effect. The Company

                                       1

<PAGE>

shall be entitled to obtain,  as a condition  precedent  to its  issuance of any
certificates  representing  Warrant Shares or any other securities issuable upon
any  exercise  of the  Warrant,  a letter or other  instrument  from the  Holder
containing  such  covenants,  representations  or  warranties  by such Holder as
reasonably  deemed necessary by Company to effect compliance by the Company with
the requirements of applicable federal and/or state securities laws.

                  2.3  Transfer.  Subject to Section 2.2,  the Warrant  shall be
transferable only on the Warrant Register upon delivery thereof duly endorsed by
the Holder or by his duly authorized attorney or representative,  or accompanied
by proper  evidence of  succession,  assignment or authority to transfer,  which
endorsement shall be guaranteed by a bank or trust company or a broker or dealer
which is a member of the National Association of Securities Dealers, Inc. In all
cases of transfer by an attorney, the original power of attorney, duly approved,
or a copy  thereof,  duly  certified,  shall be  deposited  and remain  with the
Company (or the Warrant Agent, if appointed).  In case of transfer by executors,
administrators,  guardians or other legal  representatives,  duly  authenticated
evidence  of  their  authority  shall be  produced,  and may be  required  to be
deposited  and remain with the Company (or the Warrant  Agent,  if appointed) in
its discretion. Upon any registration of transfer, the Company shall execute and
deliver (or if appointed, the Warrant Agent shall countersign and deliver) a new
Warrant or Warrants to the persons entitled thereto.

                  2.4  Form  of  Warrant.  The  text of the  Warrant  and of the
Purchase Form shall be  substantially as set forth in Exhibit A attached hereto.
The price per  Warrant  Share and the number of  Warrant  Shares  issuable  upon
exercise of each  Warrant  are  subject to  adjustment  upon the  occurrence  of
certain events, all as hereinafter  provided.  The Warrants shall be executed on
behalf of the Company by its Chairman of the Board, President or one of its Vice
Presidents,  under  its  corporate  seal  reproduced  thereon  attested  by  its
Secretary  or Assistant  Secretary.  The  signature of any such  officers on the
Warrants may be manual or facsimile,  provided,  however,  that the signature of
any  such  officers  must be  manual  until  such  time as a  Warrant  Agent  is
appointed.

                  Warrants  bearing  the  manual  or  facsimile   signatures  of
individuals  who were at any time the proper  officers of the Company shall bind
the Company, notwithstanding that such individuals or any one of them shall have
ceased to hold such offices  prior to the  delivery of such  Warrants or did not
hold such offices on the date of this Agreement.

                  In the event that the Company shall appoint a Warrant Agent to
act on its  behalf  in  connection  with the  division,  transfer,  exchange  or
exercise of  Warrants,  the Warrants  issued after the date of such  appointment
shall be dated as of the date of  countersignature  thereof by the Warrant Agent
upon  division,  exchange,  substitution  or  transfer.  Until  such time as the
Company shall appoint a Warrant Agent, Warrants shall be dated as of the date of
execution  thereof by the Company either upon initial issuance or upon division,
exchange, substitution or transfer.

                                       2

<PAGE>

         SECTION 3.  Countersignature of Warrants. In the event that the Company
shall  appoint  a Warrant  Agent to act on its  behalf  in  connection  with the
division,  transfer, exchange or exercise of Warrants, the Warrants issued after
the date of such  appointment  shall be counter  signed by the Warrant Agent (or
any successor to the Warrant  Agent then acting as warrant  agent) and shall not
be valid for any purpose unless so countersigned. Warrants may be countersigned,
however,  by the Warrant Agent (or by its successor as warrant agent  hereunder)
and may be  delivered  by the Warrant  Agent,  notwithstanding  that the persons
whose manual or facsimile  signatures  appear thereon as proper  officers of the
Company   shall  have   ceased  to  be  such   officers  at  the  time  of  such
countersignature,  issuance or  delivery.  The Warrant  Agent (if so  appointed)
shall, upon written instructions of the Chairman of the Board, the President, an
Executive  or Senior Vice  President,  the  Treasurer or the  Controller  of the
Company,  countersign,  issue and deliver Warrants entitling the Holders thereof
to purchase not more than 30,000 Warrant Shares (subject to adjustment  pursuant
to Section 10 hereof) and shall  countersign  and deliver  Warrants as otherwise
provided in this Agreement.

         SECTION 4. Exchange of Warrant  Certificates.  Each Warrant certificate
may be  exchanged,  at the option of the Holder  thereof,  for  another  Warrant
certificate or Warrant  certificates  in different  denominations  entitling the
Holder or Holders thereof to purchase a like aggregate  number of Warrant Shares
as the  certificate  or  certificates  surrendered  then  entitle each Holder to
purchase.  Any Holder desiring to exchange a Warrant certificate or certificates
shall make such  request in writing  delivered  to the Company at its  principal
office (or, if a Warrant Agent is appointed,  the Warrant Agent at its principal
office) and shall surrender,  properly endorsed, the certificate or certificates
to be so exchanged. Thereupon, the Company (or, if appointed, the Warrant Agent)
shall  execute  and  deliver  to  the  person  entitled  thereto  a new  Warrant
certificate or certificates,  as the case may be, as so requested,  in such name
or names as such Holder shall designate.

         SECTION 5. Exercise of Warrants; Listing.

                  5.1  Exercise of  Warrants.  A Warrant may be  exercised  upon
surrender  of the  certificate  or  certificates  evidencing  the Warrants to be
exercised, together with the form of election to purchase on the reverse thereof
duly filled in and signed,  which  signature  shall be  guaranteed  by a bank or
trust  company  or a  broker  or  dealer  which  is a  member  of  the  National
Association of Securities Dealers,  Inc., to the Company at its principal office
(or if appointed, the principal office of the Warrant Agent) and upon payment of
the  Warrant  Price  (as  defined  in and  determined  in  accordance  with  the
provisions of Sections 9 and 10 hereof) to the Company (or if appointed,  to the
Warrant Agent for the account of the Company),  for the number of Warrant Shares
in respect of which such Warrants are then  exercised.  Payment of the aggregate
Warrant  Price  (defined  in  Section  9  herein)  shall  be  made in cash or by
certified or bank cashier's check.

                                       3

<PAGE>

                  Subject to Section 6 hereof, upon the surrender of the Warrant
and payment of the Warrant Price as aforesaid, the Company (or if appointed, the
Warrant  Agent)  shall  cause to be issued  and  delivered  with all  reasonable
dispatch to or upon the written order of the Holder and in such name or names as
the Holder may designate,  a certificate or certificates  for the number of full
Warrant  Shares so purchased  upon the exercise of such  Warrant,  together with
cash,  as provided in Section 11 hereof,  in respect of any  fractional  Warrant
Shares otherwise issuable upon such surrender.  Such certificate or certificates
shall be deemed to have been  issued  and any person so  designated  to be named
therein shall be deemed to have become a holder of record of such Warrant Shares
as of the date of the  surrender  of such  Warrants  and  payment of the Warrant
Price, as aforesaid.  The rights of purchase represented by the Warrant shall be
exercisable,  at the election of the Holder thereof, either in full or from time
to time in part and, in the event that a certificate  evidencing  the Warrant is
exercised in respect of less than all of the Warrant Shares  purchasable on such
exercise  at any time  prior to the date of  expiration  of the  Warrant,  a new
certificate  evidencing the  unexercised  portion of the Warrant will be issued,
and the Warrant  Agent (if so  appointed)  is hereby  irrevocably  authorized to
countersign and to deliver the required new Warrant  certificate or certificates
pursuant  to the  provisions  of this  Section  and  Section 3  hereof,  and the
Company, whenever required by the Warrant Agent (if appointed),  will supply the
Warrant Agent with Warrant  certificates  duly executed on behalf of the Company
for such purpose.

                  5.2 Listing of Shares on  Securities  Exchange;  Exchange  Act
Registration.  The  Company  will  promptly  use its best  efforts  to cause the
Warrant  Shares to be listed,  subject to official  notice of  issuance,  on all
national  securities  exchanges  on which the  Common  Stock is listed and whose
rules and regulations  require such listing,  as soon as possible  following the
date hereof.

                  The Company will promptly notify the Holders in the event that
the Company  plans to register the  Warrants  with the  Securities  and Exchange
Commission under the Securities  Exchange Act of 1934, as amended (the "Exchange
Act").

         SECTION 6. Payment of Taxes. The Company will pay all documentary stamp
taxes, if any,  attributable to the initial  issuance of Warrant Shares upon the
exercise of Warrants;  provided, however, that the Company shall not be required
to pay any tax or taxes which may be payable in respect of any transfer involved
in the issue or delivery of any Warrant or certificates  for Warrant Shares in a
name other than that of the registered Holder of such Warrants.

         SECTION  7.  Mutilated  or  Missing  Warrants.   In  case  any  of  the
certificates  evidencing  the  Warrants  shall be  mutilated,  lost,  stolen  or
destroyed,  the  Company  may in its  discretion  issue  and  deliver  (and,  if
appointed,  the Warrant  Agent shall  countersign  and  deliver) in exchange and
substitution for and upon cancellation of the mutilated Warrant certificate,  or
in  lieu of and  substitution  for  the  Warrant  certificate  lost,  stolen  or
destroyed,  a new Warrant  certificate  of like tenor,  but only upon receipt of
evidence  reasonably  satisfactory  to the Company and the Warrant  Agent (if so
appointed) of such loss,  theft or  destruction of such

                                       4

<PAGE>

Warrant and an indemnity or bond, if requested,  also reasonably satisfactory to
them. An applicant for such a substitute  Warrant  certificate shall also comply
with such other reasonable  regulations and pay such other reasonable charges as
the Company (or the Warrant Agent, if so appointed) may prescribe.

         SECTION 8. Reservation of Warrant Shares;  Purchase and Cancellation of
Warrants.

                  8.1 Reservation of Warrant  Shares.  There have been reserved,
and the Company shall at all times keep reserved,  out of its authorized  Common
Stock, a number of shares of Common Stock sufficient to provide for the exercise
of the  rights of  purchase  represented  by the  outstanding  Warrants  and any
additional Warrants issuable hereunder.  The Transfer Agent for the Common Stock
and every  subsequent  transfer  agent for any shares of the  Company's  capital
stock issuable upon the exercise of any of the rights of purchase aforesaid will
be  irrevocably  authorized  and directed at all times to reserve such number of
authorized shares as shall be required for such purpose. The Company will keep a
copy of this  Agreement on file with the Transfer Agent for the Common Stock and
with every  subsequent  transfer  agent for any shares of the Company's  capital
stock  issuable upon the exercise of the rights of purchase  represented  by the
Warrants.  The Warrant Agent,  if appointed,  will be irrevocably  authorized to
requisition  from time to time from such Transfer  Agent the stock  certificates
required to honor outstanding  Warrants upon exercise thereof in accordance with
the terms of this  Agreement.  The Company will supply such Transfer  Agent with
duly executed stock certificates for such purposes and will provide or otherwise
make  available  any cash which may be payable as provided in Section 11 hereof.
The  Company  will  furnish  such  Transfer  Agent  a  copy  of all  notices  of
adjustments  and  certificates  related  thereto,  transmitted  to  each  Holder
pursuant to subsection 10.3 hereof.

                  8.2  Purchase of Warrants by the  Company.  The Company  shall
have the right,  except as limited by law, other agreements or herein,  with the
consent of the Holder,  to purchase or otherwise acquire Warrants at such times,
in such manner and for such consideration as it may deem appropriate.

                  8.3  Cancellation of Warrants.  In the event the Company shall
purchase or otherwise  acquire  Warrants,  the same shall thereupon be cancelled
and  retired.  The  Warrant  Agent (if so  appointed)  shall  cancel any Warrant
surrendered  for  exchange,  substitution,  transfer  or exercise in whole or in
part.

         SECTION 9.  Warrant  Price.  Subject  to any  adjustments  required  by
Section  10  hereof,  the  price  per  share at which  Warrant  Shares  shall be
purchasable  upon  exercise  of a Warrant  (as to any  particular  Warrant,  the
"Warrant Price") shall be Four Dollars ($4.00) per share.

                                       5

<PAGE>

         SECTION 10.  Adjustment of Warrant Price and Number of Warrant  Shares.
The number and kind of securities  purchasable upon the exercise of each Warrant
and the Warrant Price shall be subject to adjustment  from time to time upon the
happening of certain events, as hereinafter defined.

                  10.1  Adjustments.  The number of Warrant  Shares  purchasable
upon the  exercise of each  Warrant  and the  Warrant  Price shall be subject to
adjustment as follows:

                           (a) In the  event  that the  Company  shall (i) pay a
dividend in shares of Common  Stock or make a  distribution  in shares of Common
Stock, (ii) subdivide its outstanding  shares of Common Stock, (iii) combine its
outstanding  shares of Common  Stock  into a smaller  number of shares of Common
Stock or (iv) reclassify or change  (including a change to the right to receive,
or a change  into,  as the case may be (other  than with  respect to a merger or
consolidation  pursuant to the exercise of appraisal  rights),  shares of stock,
other securities,  property,  cash or any combination  thereof) its Common Stock
(including   any  such   reclassification   or  change  in  connection   with  a
consolidation or merger in which the Company is the surviving corporation),  the
number of Warrant Shares  purchasable upon exercise of each Warrant  immediately
prior  thereto  shall be  adjusted so that the Holder of each  Warrant  shall be
entitled to receive the kind and number of Warrant Shares or other securities of
the Company or other property which he would have owned or have been entitled to
receive  after the  happening  of any of the events  described  above,  had such
Warrant been exercised  immediately  prior to the happening of such event or any
record date with respect thereto.  An adjustment made pursuant to this paragraph
(a) shall become  effective  immediately  after the effective date of such event
retroactive to the record date, if any, for such event.

                           (b) In case the Company shall issue  rights,  options
or warrants to all holders of its outstanding  Common Stock,  without any charge
to such holders,  entitling  them to subscribe for or purchase  shares of Common
Stock at a price per share  which is lower at the record  date  mentioned  below
than the then  current  market  price per share of Common  Stock (as  defined in
paragraph (d) below),  the number of Warrant Shares thereafter  purchasable upon
the exercise of each Warrant shall be determined  by  multiplying  the number of
Warrant  Shares  theretofore  purchasable  upon  exercise  of each  Warrant by a
fraction,  of which the numerator  shall be the number of shares of Common Stock
outstanding on the date of issuance of such rights, options or warrants plus the
number of additional shares of Common Stock offered for subscription or purchase
in  connection  with  such  rights,  options  or  warrants,  and  of  which  the
denominator  shall be the number of shares of Common  Stock  outstanding  on the
date of issuance of such rights,  options or warrants  plus the number of shares
which the aggregate offering price of the total number of shares of Common Stock
so offered would  purchase at the current market price per share of Common Stock
at such record date. Such adjustment shall be made whenever such rights, options
or warrants are issued, and shall become effective  immediately after the record
date for the  determination  of  stockholders  entitled to receive  such rights,
options or warrants.

                           (c) In  case  the  Company  shall  distribute  to all
holders of its  shares of Common  Stock,  (including  any  distribution  made in
connection  with a merger in which the  Company is the  surviving  corporation),
evidences  of  its  indebtedness  or  assets   (excluding  cash,   dividends  or
distributions  payable  out of  consolidated  earnings  or  earned  surplus  and
dividends  or  distributions  referred  to in  paragraph  (a)  above) or rights,
options or warrants,  or convertible or exchangeable  securities  containing the
right to  subscribe  for or purchase  shares of Common

                                       6

<PAGE>

Stock  (excluding  those referred to in paragraph (b) above),  then in each case
the number of Warrant Shares  thereafter  purchasable  upon the exercise of each
Warrant  shall be  determined  by  multiplying  the  number  of  Warrant  Shares
theretofore  purchasable  upon the  exercise of each  Warrant by a fraction,  of
which the numerator  shall be the then current  market price per share of Common
Stock (as defined in paragraph (d) below) on the date of such distribution,  and
of which the  denominator  shall be the then  current  market price per share of
Common Stock,  less the then fair value (as determined by the Board of Directors
of the Company or, in the case of Warrants  held by the Lender,  an  independent
investment  banker  which  shall be mutually  agreeable  to the  parties,  whose
determination,  in each case,  shall be conclusive) of the portion of the assets
or evidences of  indebtedness  so  distributed or of such  subscription  rights,
options  or  warrants,  or  of  such  convertible  or  exchangeable   securities
applicable to one share of Common Stock.  Such adjustment shall be made whenever
any such  distribution  is  made,  and  shall  become  effective  on the date of
distribution   retroactive  to  the  record  date  for  the   determination   of
shareholders entitled to receive such distribution.

                           (d)  For  the  purpose  of  any   computation   under
paragraphs  (b) and (c) of this Section,  the current  market price per share of
Common  Stock at any date shall be the average of the daily last sale prices for
the 20 consecutive trading days ending one trading day prior to the date of such
computation.  The closing  price for each day shall be the last  reported  sales
price regular way or, in case no such reported sale takes place on such day, the
average of the  closing bid and asked  prices  regular way for such day, in each
case on the principal national securities exchange on which the shares of Common
Stock are listed or  admitted  to trading  or, if not so listed or  admitted  to
trading,  the last sale price of the Common  Stock on the Nasdaq Stock Market or
any comparable system. If the current market price of the Common Stock cannot be
so determined,  the Board of Directors of the Company shall reasonably determine
the current market price on the basis of such quotations as are available.

                           (e) No  adjustment  in the number of  Warrant  Shares
purchasable  hereunder shall be required unless such adjustment would require an
increase  or  decrease  of at least one  percent  (1%) in the  number of Warrant
Shares purchasable upon the exercise of each Warrant;  provided,  however,  that
any  adjustments  which by reason of this  paragraph  (e) are not required to be
made  shall  be  carried  forward  and  taken  into  account  in any  subsequent
adjustment. All calculations shall be made with respect to the number of Warrant
Shares purchasable  hereunder,  to the nearest tenth of a share and with respect
to the Warrant Price payable hereunder, to the nearest whole cent.

                           (f) Whenever the number of Warrant Shares purchasable
upon the exercise of each Warrant is adjusted,  as herein provided,  the Warrant
Price  payable upon  exercise of each Warrant  shall be adjusted by  multiplying
such Warrant Price immediately prior to such adjustment by a fraction,  of which
the  numerator  shall be the  number  of  Warrant  Shares  purchasable  upon the
exercise of each Warrant immediately prior to such adjustment,  and of which the
denominator  shall be the  number  of  Warrant  Shares  purchasable  immediately
thereafter.

                                       7

<PAGE>

                           (g) No  adjustment  in the number of  Warrant  Shares
purchasable  upon the exercise of each Warrant need be made under paragraphs (b)
and (c) if the Company  issues or  distributes  to each  Holder of Warrants  the
rights  options,   warrants,  or  convertible  or  exchangeable  securities,  or
evidences of indebtedness or assets referred to in those  paragraphs  which each
Holder of Warrants  would have been  entitled to receive had the  Warrants  been
exercised  prior to the  happening of such event or the record date with respect
thereto. No adjustment need be made for a change in the par value of the Warrant
Shares.

                           (h) For the purpose of this subsection 10.1, the term
"shares of Common  Stock"  shall mean (i) the class of stock  designated  as the
Common  Stock of the  Company at the date of this  Agreement,  or (ii) any other
class of stock resulting from successive  changes or  reclassifications  of such
shares  consisting  solely of changes in par value,  or from par value to no par
value,  or from no par value to par value.  In the event that at any time,  as a
result of an adjustment made pursuant to paragraph (a) above,  the Holders shall
become  entitled to purchase any  securities of the Company other than shares of
Common Stock,  thereafter  the number of such other shares so  purchasable  upon
exercise of each  Warrant and the Warrant  Price of such shares shall be subject
to adjustment from time to time in a manner and on terms as nearly equivalent as
practicable  to the provisions  with respect to the Warrant Shares  contained in
paragraphs  (a) through  (i),  inclusive,  and the  provisions  of Section 5 and
subsections  10.2 through 10.5,  inclusive,  with respect to the Warrant Shares,
shall apply on like terms to any such other securities.

                           (i)  Upon  the  expiration  of any  rights,  options,
warrants or  conversion  or exchange  privileges,  if any thereof shall not have
been exercised,  the Warrant Price and the number of Warrant Shares  purchasable
upon the exercise of each Warrant shall, upon such expiration, be readjusted and
shall  thereafter be such as it would have been had it been originally  adjusted
(or had the original adjustment not been required, as the case may be) as if (A)
the only shares of Common  Stock so issued were the shares of Common  Stock,  if
any, actually issued or sold upon the exercise of such rights, options, warrants
or  conversion or exchange  rights and (B) such shares of Common Stock,  if any,
were issued or sold for the consideration  actually received by the Company upon
such exercise plus the aggregate consideration, if any, actually received by the
Company for the issuance, sale or grant of all such rights, options, warrants or
conversion or exchange rights whether or not exercised.

                  10.2 Voluntary  Adjustment by the Company.  The Company may at
its option, at any time during the term of the Warrants, reduce the then current
Warrant Price to any amount deemed  appropriate by the Board of Directors of the
Company.

                  10.3  Notice of  Adjustment.  Whenever  the  number of Warrant
Shares  purchasable  upon the exercise of each  Warrant or the Warrant  Price of
such Warrant Shares is adjusted,  as herein  provided,  the Company shall, or in
the event that a Warrant Agent is appointed, the Company shall cause the Warrant
Agent promptly to, mail by first class,  postage prepaid,  to each Holder notice
of such  adjustment  or  adjustments.  Such notice shall set forth the number of
Warrant  Shares  purchasable  upon the  exercise of each Warrant and the Warrant
Price

                                       8

<PAGE>

of such Warrant Shares after such adjustment, setting forth a brief statement of
the facts  requiring such  adjustment and setting forth the computation by which
such adjustment was made.

                  10.4 No  Adjustment  for  Dividends.  Except  as  provided  in
subsection  10.1, no adjustment in respect of any dividends shall be made during
the term of a Warrant or upon the exercise of a Warrant.

                  10.5    Preservation   of   Purchase   Rights   Upon   Merger,
Consolidation,  etc. In case of any  consolidation of the Company with or merger
of the Company  into  another  corporation  or in case of any sale,  transfer or
lease to another  corporation  of all or  substantially  all the property of the
Company,  the Company or such successor or purchasing  corporation,  as the case
may be,  shall  execute  an  agreement  that each  Holder  shall  have the right
thereafter,  upon such Holder's election, either (i) upon payment of the Warrant
Price in effect  immediately  prior to such action, to purchase upon exercise of
each  Warrant the kind and amount of shares and other  securities  and  property
(including  cash)  which he would  have owned or have been  entitled  to receive
after the happening of such consolidation,  merger,  sale, transfer or lease had
such Warrant been  exercised  immediately  prior to such action (such shares and
other  securities and property  (including  cash) being referred to as the "Sale
Consideration") or (ii) to receive, in cancellation of such Warrant (and in lieu
of paying the Warrant price and exercising such Warrant), the Sale Consideration
less a portion  thereof having a fair market value (as reasonably  determined by
the Company) equal to the Warrant Price (it being  understood  that, if the Sale
Consideration  consists  of more than one type of shares,  other  securities  or
property,  the amount of each type of shares, other securities or property to be
received  shall  be  reduced  proportionately);   provided,   however,  that  no
adjustment  in respect of  dividends,  interest or other  income on or from such
shares or other  securities  and  property  shall be made  during  the term of a
Warrant or upon the exercise of a Warrant. The Company shall mail by first class
mail,  postage  prepaid,  to each  Holder,  notice of the  execution of any such
agreement.  Such  agreement  shall  provide for  adjustments,  which shall be as
nearly equivalent as may be practicable to the adjustments  provided for in this
Section 10. The  provisions of this  subsection  10.5 shall  similarly  apply to
successive  consolidations,  mergers,  sales,  transfers or leases.  The Warrant
Agent (if appointed) shall be under no duty or  responsibility  to determine the
correctness  of any provisions  contained in any such agreement  relating to the
kind or amount of shares of stock or other  securities  or  property  receivable
upon  exercise of Warrants or with  respect to the method  employed and provided
therein for any  adjustments  and shall be entitled to rely upon the  provisions
contained in any such agreement.

                  10.6 Statement on Warrants. Irrespective of any adjustments in
the Warrant Price or the number or kind of shares  purchasable upon the exercise
of the Warrants, Warrants issued before or after such adjustment may continue to
express  the same  price and  number  and kind of  shares  as are  stated in the
Warrants initially issuable pursuant to this Agreement.

         SECTION 11. Fractional Interests.  The Company shall not be required to
issue  fractional  Warrant Shares on the exercise of Warrants.  If more than one
Warrant  shall be  presented  for  exercise in full at the same time by the same
Holder,  the number of full  Warrant

                                       9

<PAGE>

Shares which shall be issuable  upon the exercise  thereof  shall be computed on
the basis of the aggregate  number of Warrant Shares  purchasable on exercise of
the Warrants so presented.  If any fraction of a Warrant Share would, except for
the  provisions  of this  Section 11, be issuable on the exercise of any Warrant
(or specified portion thereof), the Company shall pay an amount in cash equal to
the average of the daily  closing sale prices  (determined  in  accordance  with
paragraph  (d) of  subsection  10.1)  per  share  of  Common  Stock  for  the 20
consecutive trading days ending one trading day prior to the date the Warrant is
presented for exercise, multiplied by such fraction.

         SECTION  12. No Rights as  Shareholders;  Notices to  Holders.  Nothing
contained  in this  Agreement  or in any of the  Warrants  shall be construed as
conferring upon the Holders or their transferees the right to vote or to receive
dividends or to consent or to receive notice as  shareholders  in respect of any
meeting of  shareholders  for the  election of  directors  of the Company or any
other matter,  or any rights  whatsoever  as  shareholders  of the Company.  If,
however,  at any time prior to the expiration of the Warrants and prior to their
exercise, any of the following events shall occur:

                  (a) the  Company  shall  declare any  dividend  payable in any
securities upon its shares of Common Stock or make any distribution  (other than
a regular cash dividend, as such dividend may be increased from time to time, or
a dividend  payable in shares of Common  Stock) to the  holders of its shares of
Common Stock; or

                  (b) the  Company  shall  offer to the holders of its shares of
Common Stock on a pro rata basis any cash,  additional shares of Common Stock or
other  securities  of the Company or any right to subscribe  for or purchase any
thereof; or

                  (c) a  dissolution,  liquidation  or winding up of the Company
(other than in connection with a consolidation,  merger, sale, transfer or lease
of all  or  substantially  all  of its  property,  assets,  and  business  as an
entirety) shall be proposed,

then in any one or more of said  events  the  Company  shall (a) give  notice in
writing of such event as provided  in Section 14 hereof and (b) if the  Warrants
have been  registered  pursuant  to the Act,  cause  notice of such  event to be
published once in The Wall Street  Journal  (national  edition),  such giving of
notice and  publication to be completed at least 10 days prior to the date fixed
as a record date or the date of closing the transfer books for the determination
of the  stockholders  entitled to such dividend,  distribution,  or subscription
rights  or for  the  determination  of  stockholders  entitled  to  vote on such
proposed  dissolution,  liquidation  or winding up or the date of  expiration of
such offer.  Such notice  shall  specify such record date or the date of closing
the transfer  books or the date of  expiration,  as the case may be.  Failure to
publish, mail or receive such notice or any defect therein or in the publication
or mailing  thereof  shall not affect the  validity of any action in  connection
with such  dividend,  distribution  or  subscription  rights,  or such  proposed
dissolution, liquidation or winding up, or such offer.

                                       10

<PAGE>

         SECTION 13.  Appointment of Warrant Agent.  At such time as the Company
shall register Warrants under the Act, the Company shall appoint a Warrant Agent
to act on behalf of the  Company  in  connection  with the  issuance,  division,
transfer  and  exercise  of  Warrants.  At such time as the  Company  appoints a
Warrant  Agent,  the Company shall enter into a new Warrant  Agreement  with the
Warrant  Agent   pursuant  to  which  all  new  Warrants  will  be  issued  upon
registration of transfer or division,  which will reflect the appointment of the
Warrant Agent, as well as additional customary provisions as shall be reasonably
requested by the Warrant Agent in connection with the performance of its duties.
In the event that a Warrant Agent is  appointed,  the Company shall (i) promptly
notify the Holders of such  appointment  and the place  designated for transfer,
exchange and exercise of the Warrants, and (ii) take such steps as are necessary
to insure that Warrants  issued prior to such  appointment  may be exchanged for
Warrants countersigned by the Warrant Agent.

         SECTION 14.  Notices;  Principal  Office.  Any notice  pursuant to this
Agreement  by  the  Company  or by  any  Holder  to  the  Warrant  Agent  (if so
appointed),  or by the Warrant  Agent (if so  appointed) or by any Holder to the
Company,  shall be in writing and shall be delivered in person,  or mailed first
class, postage prepaid (a) to the Company, at its office,  Attention:  President
or (b) to the  Warrant  Agent,  at its  offices  as  designated  at the time the
Warrant Agent is appointed.  The address of the principal  office of the Company
is 935 Pardee Street,  Berkeley,  California  94710.  Each party hereto may from
time to time change the address to which  notices to it are to be  delivered  or
mailed hereunder by notice to the other party.

                  Any notice mailed pursuant to this Agreement by the Company or
the Warrant  Agent to the Holders  shall be in writing and shall be mailed first
class,  postage  prepaid,  or  otherwise  delivered,  to such  Holders  at their
respective  addresses on the books of the Company or the Warrant  Agent,  as the
case may be.

         SECTION 15.  Successors.  Except as  expressly  provided  herein to the
contrary,  all the  covenants  and  provisions  of this  Agreement by or for the
benefit of the  Company  and the Lender  shall bind and inure to the  benefit of
their respective successors and permitted assigns hereunder.

         SECTION 16. Merger or  Consolidation  of the Company.  The Company will
not  merge or  consolidate  with or  into,  or sell,  transfer  or lease  all or
substantially all of its property to, any other corporation unless the successor
or  purchasing  corporation,  as the  case  may be (if not the  Company),  shall
expressly assume, by supplemental  agreement,  the due and punctual  performance
and  observance of each and every covenant and condition of this Agreement to be
performed and observed by the Company.

                                       11

<PAGE>

         SECTION 17. Investment Representations.  Lender represents and warrants
to BioTime that:

                  17.1 Lender has received the  Company's  financial  statements
for the year ended on December  31,  2001,  as will be included in its Form 10-K
for such fiscal year,  its annual  report on Form 10-K for the fiscal year ended
December 31, 2000, and quarterly  report on Form 10-Q for the fiscal quarter and
nine months ended  September 30, 2001 (the  "Disclosure  Documents").  Lender is
relying on the  information  provided in the  Disclosure  Documents or otherwise
communicated  to Lender in writing by the Company.  Lender has not relied on any
statement or representations inconsistent with those contained in the Disclosure
Documents.  Lender has had a  reasonable  opportunity  to ask  questions  of and
receive answers from the executive officers and directors of the Company, or one
or more  of its  officers,  concerning  the  Company  and to  obtain  additional
information,  to the extent possessed or obtainable without  unreasonable effort
or expense, necessary to verify the information in the Disclosure Documents. All
such questions have been answered to Lender's satisfaction;

                  17.2  Lender  understands  that the  Warrant  and the  Warrant
Shares  are  being  offered  and  sold  without  registration  under  the Act or
qualification  under the California  Corporate  Securities Law of 1968, or under
the laws of other states, in reliance upon the exemptions from such registration
and qualification requirements for non-public offerings. Lender acknowledges and
understands  that the availability of the aforesaid  exemptions  depends in part
upon the accuracy of certain of the representations, declarations and warranties
contained  herein,  which  Lender  hereby makes with the intent that they may be
relied  upon by the  Company  and its  officers  and  directors  in  determining
Lender's suitability to acquire the Warrant. Lender understands and acknowledges
that no federal,  state or other agency has reviewed or endorsed the offering of
the Warrant or the Warrant Shares or made any finding or determination as to the
fairness of the offering or  completeness  of the  information in the Disclosure
Documents;

                  17.3  Lender  understands  that the  Warrant  and the  Warrant
Shares may not be offered,  sold, or transferred in any manner,  and the Warrant
may not be exercised,  unless  subsequently  registered under the Act, or unless
there is an exemption from such  registration  available for such offer, sale or
transfer;

                  17.4 Lender has such knowledge and experience in financial and
business  matters to enable Lender to utilize the  information  contained in the
Disclosure  Documents,  or  otherwise  made  available to Lender to evaluate the
merits and risks of an investment  in the Warrant and the Warrant  Shares and to
make an informed investment decision with respect thereto.

                  17.5 Lender is acquiring  the Warrant  solely for Lender's own
account and for long-term  investment  purposes,  and not with a view to, or for
sale in connection with, any distribution of the Warrant or Warrant Shares; and

                                       12

<PAGE>

                  17.6  Lender  is an  "accredited  investor,"  as such  term is
defined in Regulation D promulgated under the Act.

         SECTION 18. Registration Rights.

                  18.1 The Company agrees, at its expense,  upon written request
from the Lender,  to register  under the Act, the Warrant and the Warrant Shares
and to take such other  actions as may be necessary to allow the Warrant and the
Warrant Shares to be freely tradable,  without restrictions,  in compliance with
all regulatory  requirements.  A written request for registration  shall specify
the quantity of the Warrant Shares intended to be sold, the plan of distribution
and the identity of the sellers,  which may include the Lender and  assignees of
its rights hereunder  (collectively,  "Selling Securities Holders"), and whether
the  registration  shall be pursuant  to an  underwritten  public  offering or a
"shelf'  registration  pursuant to Rule 415 (or similar rule that may be adopted
by the Securities and Exchange  Commission).  The Company shall not be obligated
to file more than two such  registration  statements,  other  than  registration
statements  on Form S-3.  The Company  shall keep such  registration  statements
effective  for a period  of at  least  nine  months,  except  that  registration
statements  on Form S-3 shall be kept  effective  for at least  three years ( or
such  lesser  period  as the  parties  may  agree,  but in no event  beyond  the
completion of the  distribution or distributions  being made pursuant  thereto).
The Company  shall  utilize Form S-3 if it  qualifies  for such use. The Company
shall make all filings required with respect to the registration  statements and
will use its best efforts to cause such filings to become effective, so that the
Warrant and Warrant Shares being registered shall be registered or qualified for
sale under the  securities  or blue sky laws of such  jurisdictions  as shall be
reasonably  appropriate  for  distribution  of the Warrant  and  Warrant  Shares
covered by the registration  statement.  The Company will furnish to the Selling
Securities  Holders  such  numbers  of  copies  of  a  prospectus,  including  a
preliminary prospectus,  in conformity with the requirements of the Act and such
other related documents as the Selling Securities Holders may reasonably request
in order to effect the sale of the  Warrant and  Warrant  Shares.  To effect any
offering  pursuant to a registration  statement under this Section,  the Company
shall  enter  into  an  agreement  containing   customary   representations  and
warranties, and indemnification and contribution provisions, all for the benefit
of  Selling  Securities  Holders,  and,  in the case of an  Underwritten  public
offering. an underwriting  agreement with an investment banking firm selected by
the Lender and reasonably  acceptable to the Company,  containing such customary
representations and warranties, and indemnification and contribution provisions

                  18.2 If, at any time, the Company  proposes to register any of
its securities  under the Act (otherwise  than pursuant to Section 18.1 above or
on a Form S-8 if such form  cannot be used for  registration  of the  Warrant or
Warrant  Shares  pursuant  to its  terms),  the  Company  shall,  as promptly as
practicable,  give written  notice to the Lender.  The Company  shall include in
such  registration  statement the Warrant and any Warrant Shares  proposed to be
sold by the Selling Securities Holders.  Notwithstanding  the foregoing,  if the
offering of the  Company's  securities is to be made through  underwriters,  the
Company  shall not be required to include the Warrant and Warrant  Shares if and
to the extent that the managing  underwriter  reasonably  believes in good faith
that such inclusion would  materially  adversely affect such

                                       13

<PAGE>

offering  unless the Selling  Securities  Holders agree to postpone  their sales
until 10 days after the distribution is completed.

                  18.3  The  Company  shall  pay the  cost  of the  registration
statements filed pursuant to this Agreement,  including  without  limitation all
registration and filing fees, fees and expenses of compliance with securities or
blue sky laws (including  counsel's fees and expenses in connection  therewith),
printing  expenses,  messenger and delivery  expenses,  internal expenses of the
Company,  listing  fees and  expenses,  and fees and  expenses of the  Company's
counsel,  independent  accountants and other persons retained or employed by the
Company.  Selling  Securities  Holders  shall  pay  any  underwriters  discounts
applicable to the Warrant and Warrant Shares.

         SECTION 19. Legends. The Warrants and Warrant Shares issued pursuant to
this Agreement shall bear an appropriate  legend,  conspicuously  disclosing the
restrictions  on exercise and transfer under Section 2.2 of this Agreement until
the same are registered for sale under the Act. The Company agrees that upon the
sale of the Warrant and Warrant Shares  pursuant to a registration  statement or
an exemption, upon the presentation of the certificates containing such a legend
to it's transfer agent,  it will remove such legend.  The Company further agrees
to remove the legend at such time as registration  under the Act shall no longer
be required.

         SECTION 20.  Applicable  Law. This  Agreement  and each Warrant  issued
hereunder  shall be governed by and construed in accordance with the laws of the
State of California, without giving effect to principles of conflict of laws.

         SECTION 21. Benefits of this Agreement. Nothing in this Agreement shall
be construed to give to any person or  corporation  other than the Company,  the
Warrant  Agent (if  appointed)  and the  Holders any legal or  equitable  right,
remedy or claim under this  Agreement;  but this Agreement shall be for the sole
and exclusive  benefit of the Company,  the Warrant Agent and the Holders of the
Warrants.

         SECTION 22. Counterparts.  This Agreement may be executed in any number
of counterparts and each of such  counterparts  shall for all purposes be deemed
to be an original,  and all such counterparts shall together  constitute but one
and the same instrument.

         SECTION 23.  Captions.  The captions of the Sections and subsections of
this  Agreement  have been  inserted  for  convenience  only and  shall  have no
substantive effect.

                                       14

<PAGE>

         IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
duly executed, all as of the day and year first above written.

                                            BIOTIME, INC.

                                            By: ________________________________
                                               Name: Paul Segall, Ph.D
                                               Title: Chairman and Chief
                                                      Executive Officer

Attest:

By: ______________________________
    Name: Judith Segall
    Title: Secretary

                                            ____________________________________
                                                       Alfred D. Kingsley

                                       15

<PAGE>

                                                                       EXHIBIT A

         THIS WARRANT HAS NOT BEEN REGISTERED  UNDER THE SECURITIES ACT OF 1933,
AS AMENDED,  OR UNDER  APPLICABLE STATE SECURITIES LAWS. THIS WARRANT MAY NOT BE
EXERCISED, SOLD, PLEDGED, HYPOTHECATED,  TRANSFERRED OR ASSIGNED EXCEPT UNDER AN
EFFECTIVE  REGISTRATION STATEMENT UNDER SUCH ACT AND APPLICABLE STATE SECURITIES
LAWS, UNLESS AN EXEMPTION FROM SUCH REGISTRATION IS AVAILABLE.

               VOID AFTER 5:00 P.M. NEW YORK TIME, March 26, 2007

Certificate No. ______                                       Warrant to Purchase
                                                       [Insert number of Shares]
                                                          Shares of Common Stock

                                  BIOTIME, INC.
                         COMMON SHARE PURCHASE WARRANTS

         This  certifies  that, for value  received,  [Insert name of Holder] or
registered assigns (the "Holder"),  is entitled to purchase from BioTime, Inc. a
California  corporation (the  "Company"),  at a purchase price per share [Insert
Warrant Price determined pursuant to Sections 9 and 10 of the Warrant Agreement]
(the "Warrant  Price"),  the number of its Common Shares, no par value per share
(the  "Common  Stock"),  shown  above.  The  number of shares  purchasable  upon
exercise of the Common Share Purchase  Warrants (the "Warrants") and the Warrant
Price are  subject to  adjustment  from time to time as set forth in the Warrant
Agreement  referred to below.  Outstanding  Warrants not exercised prior to 5:00
p.m., New York time, on March 26, 2007 shall thereafter be void.

         Subject to restriction specified in the Warrant Agreement, Warrants may
be exercised  in whole or in part by  presentation  of this Warrant  Certificate
with the Purchase Form on the reverse side hereof duly executed, which signature
shall be  guaranteed by a bank or trust company or a broker or dealer which is a
member of the National Association of Securities Dealers, Inc., and simultaneous
payment of the Warrant  Price (or as otherwise set forth in Section 10.5) of the
Warrant  Agreement at the principal office of the Company (or if a Warrant Agent
is appointed,  at the principal  office of the Warrant  Agent).  Payment of such
price shall be made in cash or by certified or bank cashier's check. As provided
in the Warrant  Agreement,  the  Warrant  Price and the number or kind of shares
which may be  purchased  upon the  exercise  of the  Warrant  evidenced  by this
Warrant  Certificate  are,  upon the  happening  of certain  events,  subject to
modification and adjustment.

                                       16

<PAGE>

         This  Warrant  Certificate  is issued  under and in  accordance  with a
Warrant  Agreement  dated as of March 27, 2002 between the Company and Alfred D.
Kingsley  and is subject to the terms and  provisions  contained  in the Warrant
Agreement,  to all of which the Holder of this Warrant Certificate by acceptance
of this Warrant  Certificate  consents.  A copy of the Warrant  Agreement may be
obtained by the Holder hereof upon written request to the Company.  In the event
that  pursuant  to  Section  13 of the  Warrant  Agreement  a  Warrant  Agent is
appointed and a new warrant  agreement entered into between the Company and such
Warrant  Agent,  then such new warrant  agreement  shall  constitute the Warrant
Agreement for purposes  hereof and this Warrant  Certificate  shall be deemed to
have been issued pursuant to such new warrant agreement.

         Upon any  partial  exercise of the Warrant  evidenced  by this  Warrant
Certificate,  there  shall  be  issued  to  the  Holder  hereof  a  new  Warrant
Certificate  in respect of the  shares of Common  Stock as to which the  Warrant
evidenced  by this  Warrant  Certificate  shall  not have been  exercised.  This
Warrant  Certificate  may be  exchanged  at the  office of the  Company  (or the
Warrant Agent, if appointed) by surrender of this Warrant  Certificate  properly
endorsed  either  separately  or in  combination  with one or more other Warrant
Certificates  for one or more new Warrant  Certificates  evidencing the right of
the  Holder  thereof  to  purchase  the  aggregate  number  of  shares  as  were
purchasable on exercise of the Warrants evidenced by the Warrant  Certificate or
Certificates exchanged. No fractional shares will be issued upon the exercise of
any  Warrant,  but the Company  will pay the cash value  thereof  determined  as
provided in the Warrant Agreement.  This Warrant  Certificate is transferable at
the office of the Company (or the Warrant Agent, if appointed) in the manner and
subject to the limitations set forth in the Warrant Agreement.

         The Holder hereof may be treated by the Company,  the Warrant Agent (if
appointed)  and all other persons  dealing with this Warrant  Certificate as the
absolute owner hereof for any purpose and as the person entitled to exercise the
rights  represented  hereby,  or to the  transfer  hereof  on the  books  of the
Company, any notice to the contrary notwithstanding,  and until such transfer on
such books,  the Company (and the Warrant  Agent,  if  appointed)  may treat the
Holder hereof as the owner for all purposes.

         Neither the Warrant nor this Warrant Certificate entitles any Holder to
any of the rights of a stockholder of the Company.

         [This  Warrant  Certificate  shall not be valid or  obligatory  for any
purpose until it shall have been countersigned by the Warrant Agent.]*

                                       17

<PAGE>

DATED:

                                                     BIOTIME, INC.

(Seal)                                               By:________________________

                                                     Title:

Attest:____________________

[COUNTERSIGNED:

                                    ,
WARRANT AGENT

By: _________________________________]*
         Authorized Signature

--------------------
*        To be part of the Warrant only after the appointment of a Warrant Agent
         pursuant to Section 13 of the Warrant Agreement.

                                       18

<PAGE>

                                  PURCHASE FORM

                    (To be executed upon exercise of Warrant)

To BioTime, Inc.:

         The  undersigned  hereby  irrevocably  elects to exercise  the right of
purchase  represented  by the within  Warrant  Certificate  for, and to purchase
thereunder,  _____ shares of Common Stock, as provided for therein,  and tenders
herewith  payment  of the  purchase  price  in  full  in the  form  of cash or a
certified or bank cashier's check in the amount of $_________.

         Please issue a certificate  or  certificates  for such shares of Common
Stock in the name of, and pay any cash for any fractional share to:

PLEASE INSERT SOCIAL SECURITY                 NAME
OR OTHER IDENTIFYING NUMBER                        (Please Print Name &
OF ASSIGNEE                                          Address)

___________________________                   Address

___________________________                   Signature

                                                   NOTE: The   above   signature
                                                         should       correspond
                                                         exactly  with  the name
                                                         on  the  face  of  this
                                                         Warrant  Certificate or
                                                         with  the  name  of the
                                                         assignee  appearing  in
                                                         the   assignment   form
                                                         below.

And, if said number of shares shall not be all the shares  purchasable under the
within  Warrant  Certificate,  a new Warrant  Certificate is to be issued in the
name of said  undersigned  for the balance  remaining  of the share  purchasable
thereunder less any fraction of a share paid in cash.

                                       19

<PAGE>

                                   ASSIGNMENT

          (To be executed only upon assignment of Warrant Certificate)

         For value received,  _____________  hereby sells, assigns and transfers
unto  _______________ the within Warrant  Certificate,  together with all right,
title and interest therein,  and does hereby irrevocably  constitute and appoint
_________________ attorney, to transfer said Warrant Certificate on the books of
the within-named Company, with full power of substitution in the premises.

Dated:___________________                       ________________________________
                                                NOTE: The above signature should
                                                      correspond   exactly  with
                                                      the  name  on the  face of
                                                      this Warrant Certificate.

                                       20

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