<PAGE> 52
                          REGISTRATION RIGHTS AGREEMENT

         This  REGISTRATION  RIGHTS  AGREEMENT (this  "Agreement") is made as of
July 28, 2000 by and among (i) BioSphere Medical,  Inc., a Delaware  corporation
(the  "Company"),   (ii)  each  person  listed  on  Exhibit  A  attached  hereto
(collectively,  the  "Initial  Investors"  and each  individually,  an  "Initial
Investor"), and (iii) each person or entity that subsequently becomes a party to
this Agreement pursuant to, and in accordance with, the provisions of Section 12
hereof (collectively, the "Investor Permitted Transferees" and each individually
an "Investor Permitted Transferee").

         WHEREAS,  the  Company  has  agreed  to issue  and sell to the  Initial
Investors,  and the Initial  Investors have agreed to purchase from the Company,
1,154,900 shares (the "Purchased  Shares") of the Company's common stock,  $0.01
par value per share (the "Common Stock"),  all upon the terms and conditions set
forth in that certain Stock  Purchase  Agreement,  dated of even date  herewith,
between the Company and the Initial Investors (the "Stock Purchase  Agreement");
and

         WHEREAS,  the terms of the Stock  Purchase  Agreement  provide  that it
shall be a condition precedent to the closing of the transactions thereunder for
the Company and the Initial Investors to execute and deliver this Agreement.

         NOW,  THEREFORE,  in consideration of the premises and mutual covenants
contained herein, the parties hereto hereby agree as follows:

1.       DEFINITIONS.  The following terms shall have the meanings provided
        therefor below or elsewhere in this Agreement as
         -----------
described below:

         "Board" shall mean the board of directors of the Company.

         "Closing"  shall have the  meaning  ascribed  to such term in the Stock
Purchase Agreement.

         "Exchange  Act"  shall mean the  Securities  Exchange  Act of 1934,  as
amended, and all of the rules and regulations promulgated thereunder.

         "Investors"  shall mean,  collectively,  the Initial  Investors and the
Investor Permitted  Transferees;  provided,  however,  that the term "Investors"
shall not include any of the Initial Investors or any of the Investor  Permitted
Transferees that ceases to own or hold any Purchased Shares.

         "Majority  Holders"  shall  mean,  at the  relevant  time of  reference
thereto, those Investors holding and/or having the right to acquire, as the case
may be, more than fifty percent (50%) of the  Registrable  Shares held by all of
the Investors.

         "Qualifying  Holder" shall have the meaning ascribed thereto in Section
12 hereof.

         "Registrable  Shares" shall mean the Purchased Shares and any shares of
capital stock issued or issuable,  from time to time, upon any reclassification,
share  combination,  share  subdivision,  stock split,  share dividend,  merger,
consolidation or similar transaction or event or otherwise as a distribution on,
in exchange for or with respect to any of the foregoing, provided, however, such
term shall not, after the Mandatory Registration  Termination Date, apply to any
such Shares.
<PAGE> 53

         "Rule 144" shall mean Rule 144 promulgated under the Securities Act and
any successor or substitute rule, law or provision.

         "SEC" shall mean the Securities and Exchange Commission.

         "Securities Act" shall mean the Securities Act of 1933, as amended, and
all of the rules and regulations promulgated thereunder.

2.       EFFECTIVENESS; TERMINATION.  This Agreement shall become effective and
         legally binding only if the Closing occurs.
         --------------------------

3.       MANDATORY REGISTRATION.
         ----------------------

(a) The Company  will  prepare and file with the SEC within  thirty (30) days of
the  date  hereof  a  registration  statement  on Form  S-3 for the  purpose  of
registering  under the Securities Act all of the  Registrable  Shares for resale
by, and for the account of, the  Investors  as selling  stockholders  thereunder
(the  "Registration  Statement").  The  Registration  Statement shall permit the
Investors to offer and sell, on a delayed or continuous  basis  pursuant to Rule
415 under the Securities Act, any or all of the Registrable  Shares. The Company
agrees to use its best  efforts to cause the  Registration  Statement  to become
effective as soon as practicable within 120 days of the date hereof. The Company
shall be required to keep the Registration  Statement  effective until such date
that  is the  earliest  of (i)  the  date  when  all of the  Registrable  Shares
registered  thereunder  shall have been sold by the  Initial  Investors  and the
Investor Permitted Transferees, or (ii) the second anniversary of the Closing or
(iii) such time as all of the Registrable  Shares  registered  thereunder can be
sold within any given three-month period without regard to the trading volume of
the Common Stock  pursuant to Rule 144,  subject to extension as set forth below
(such  earliest  date is  referred  to  herein  as the  "Mandatory  Registration
Termination  Date").  Thereafter,  the Company shall be entitled to withdraw the
Registration Statement and the Investors shall have no further right to offer or
sell any of the Registrable  Shares pursuant to the  Registration  Statement (or
any  prospectus  relating  thereto).  In the  event  the  right  of the  selling
Investors  to use  the  Registration  Statement  (and  the  prospectus  relating
thereto) is delayed or  suspended  pursuant to Sections  4(c) or 11 hereof,  the
Company shall be required to extend the Mandatory Registration  Termination Date
beyond the second  anniversary of the Closing by the same number of days as such
delay or Suspension Period (as defined in Section 11 hereof).

(b)    The offer and sale of the Registrable Shares pursuant to the Registration
Statement shall not be underwritten.

4. OBLIGATIONS OF THE COMPANY. In connection with the Company's obligation under
Section 3 hereof to file the Registration  Statement with the SEC and to use its
best efforts to cause the Registration  Statement to become effective as soon as
practicable, the Company shall, as expeditiously as reasonably possible:

(a) At all times from and after the effective date of the Registration Statement
until  the  Mandatory   Registration   Termination   Date  (such   period,   the
"Registration  Period"),  prepare  and file  with the SEC  such  amendments  and
supplements to the Registration  Statement and the prospectus used in connection
therewith as may be necessary to comply with the  provisions  of the  Securities
Act with respect to the  disposition  of all  Registrable  Shares covered by the
Registration  Statement and to use its reasonable best efforts to take all other
actions as may be necessary to ensure to the holders of  Registrable  Shares the
ability to effect the public  resale of their  Registrable  Shares  continuously
throughout the Registration Period;
<PAGE> 54

(b) Furnish to the selling  Investors  without charge such number of copies of a
prospectus,   including  a  preliminary  prospectus,   in  conformity  with  the
requirements of the Securities Act, and such other documents (including, without
limitation, prospectus amendments and supplements as are prepared by the Company
in accordance  with Section 4(a) above) as the selling  Investors may reasonably
request  in order to  facilitate  the  disposition  of such  selling  Investors'
Registrable Shares;

(c) Notify the selling  Investors  promptly,  (i) at any time when a  prospectus
relating to the  Registration  Statement is required to be  delivered  under the
Securities  Act,  of the  happening  of any  event  as a  result  of  which  the
prospectus  included in or relating to the  Registration  Statement  contains an
untrue  statement  of a material  fact or omits any fact  necessary  to make the
statements therein not misleading;  and,  thereafter,  the Company will promptly
prepare (and, when completed, give notice to each selling Investor) a supplement
or  amendment  to such  prospectus  so  that,  as  thereafter  delivered  to the
purchasers  of such  Registrable  Shares,  such  prospectus  will not contain an
untrue  statement of a material fact or omit to state any fact necessary to make
the statements  therein not misleading;  provided that upon such notification by
the Company,  the selling  Investors will not offer or sell  Registrable  Shares
until the Company has  notified  the selling  Investors  that it has  prepared a
supplement  or  amendment  to  such  prospectus  and  delivered  copies  of such
supplement or amendment to the selling Investors (it being understood and agreed
by the Company that the foregoing  proviso shall in no way diminish or otherwise
impair the Company's  obligation to promptly  prepare a prospectus  amendment or
supplement as above  provided in this Section 4(c) and deliver copies of same as
above  provided  in  Section  4(b)  hereof);  (ii)  when the  prospectus  or any
prospectus  supplement or  post-effective  amendment  has been filed,  and, with
respect to the Registration  Statement or any post-effective  amendment thereto,
when the same has become effective;  and (iii) of the issuance by the SEC of any
stop order or other  order  suspending  the  effectiveness  of the  Registration
Statement,  or any  order  issued by any state  securities  commission  or other
regulatory   authority   suspending   the   qualification   or  exemption   from
qualification  of such  Registrable  Shares under state securities or "blue sky"
laws. If at any time the Company  shall  receive any such stop order  suspending
the effectiveness of the Registration  Statement, or any such order from a state
securities commission or other regulatory  authority,  the Company shall use its
best efforts to obtain the  withdrawal  or lifting of such order at the earliest
possible time.

(d) Use commercially  reasonable efforts to register and qualify the Registrable
Shares covered by the Registration Statement under such other securities or Blue
Sky laws of such jurisdictions as shall be reasonably appropriate in the opinion
of the  Company or as may be  reasonably  requested  by the  selling  Investors,
provided that the Company shall not be required in connection  therewith or as a
condition  thereto  to qualify to do  business  or to file a general  consent to
service of process in any such states or jurisdictions, and

(e)      otherwise use its reasonable best efforts to comply with all applicable
         rules and regulations of the SEC;

(f) use its reasonable best efforts to cause all Registrable Shares to be listed
on each  securities  exchange or market,  if any,  on which the Common  Stock or
other equity securities issued by the Company are then listed; and

(g) use its reasonable  best efforts to take all other steps necessary to effect
the registration of the Registrable Shares contemplated hereby.

<PAGE> 55

5.  LIMITATION ON PUBLIC  OFFERINGS.  The Company  agrees that until the date on
which the  Registration  Statement has been  declared  effective by the SEC, the
Company will not file a  registration  statement for the purpose of  registering
for sale to the public  shares of its Common  Stock  (other than a  registration
statement on Form S-4 or S-8 or their respective  successors,  or any other form
of  registration   statement  for  a  similar  limited  purpose,  or  any  other
registration  statement  covering  only  securities  proposed  to be  issued  in
exchange  for  securities  or assets of  another  corporation).  Other than with
respect to the  securities  being  registered  pursuant to the Stock and Warrant
Purchase  Agreements,  by and between the Company and certain  investors,  dated
February 4, 2000 among the Company and certain investors, the Company shall not,
and will not agree to,  allow the  holders of any  securities  of the Company to
include  any of  their  securities  in any  Registration  Statement  under  this
Agreement without the consent of the Majority Holders.

6. FURNISH INFORMATION.  It shall be a condition precedent to the obligations of
the  Company to take any action  pursuant  to this  Agreement  that the  selling
Investors shall furnish to the Company such  information  regarding them and the
securities held by them as the Company shall reasonably  request and as shall be
required in order to effect any  registration  by the  Company  pursuant to this
Agreement.

7.  EXPENSES OF  REGISTRATION.  All  expenses  incurred in  connection  with the
registration  of the Registrable  Shares  pursuant to this Agreement  (excluding
underwriting,  brokerage and other selling commissions and discounts), including
without limitation all registration and qualification and filing fees, printing,
and fees and  disbursements  of counsel for the  Company and all other  internal
expenses of the Company, shall be borne by the Company.

8.       DELAY OF REGISTRATION.  Neither the Company nor the Investors shall
                                take any action to enjoin or otherwise delay any

registration as the result of any controversy  which might arise with respect to
the interpretation or implementation of this Agreement.

9.       INDEMNIFICATION.
         ---------------

(a) To the extent permitted by law, the Company will indemnify and hold harmless
each  selling  Investor,  any  broker/dealer  acting on  behalf  of any  selling
Investors  and  each  officer  and  director  of  such  selling  Investor,  such
broker/dealer  and each person,  if any, who controls  such selling  Investor or
broker/dealer  within the  meaning of the  Securities  Act,  against any losses,
claims,  damages  or  liabilities,  joint or  several,  to which they may become
subject under the Securities Act or otherwise,  insofar as such losses,  claims,
damages or liabilities (or actions in respect thereof) arise out of or are based
upon any untrue or alleged  untrue  statement of any material fact  contained in
the Registration  Statement,  in any preliminary  prospectus or final prospectus
relating  thereto  or in any  amendments  or  supplements  to  the  Registration
Statement or any such preliminary  prospectus or final prospectus,  or arise out
of or are  based  upon the  omission  or  alleged  omission  to state  therein a
material fact required to be stated therein, or necessary to make the statements
therein  not  misleading;   and  will  reimburse  such  selling  Investor,  such
broker/dealer or such officer,  director or controlling  person for any legal or
other expenses  reasonably  incurred by them in connection with investigating or
defending any such loss, claim, damage, liability or action; provided,  however,
that the indemnity  agreement  contained in this Section 9(a) shall not apply to
amounts paid in settlement of any such loss, claim, damage,  liability or action
if such settlement is effected without the consent of the Company (which consent
shall not be unreasonably withheld), nor shall the Company be liable in any such
case for any such loss, damage, liability or action to the extent that it arises
out of or is based upon an untrue  statement  or  alleged  untrue  statement  or
omission made in connection with the  Registration  Statement,  any preliminary,
prospectus or final prospectus relating thereto or any amendments or supplements
to the  Registration  Statement  or any  such  preliminary  prospectus  or final
prospectus,  in  reliance  upon  and  in  conformity  with  written  information
furnished expressly for use in connection with the Registration Statement or any
such  preliminary  prospectus or final  prospectus  by the selling  Investors or
controlling person with respect to them.
<PAGE> 56

(b) To the extent permitted by law, each selling Investor will severally and not
jointly indemnify and hold harmless the Company, each of its directors,  each of
its officers who have signed the Registration  Statement,  each person,  if any,
who  controls  the  Company  within the  meaning of the  Securities  Act, or any
broker/dealer acting on behalf of the Company or any selling Investors,  and all
other selling  Investors against any losses,  claims,  damages or liabilities to
which  the  Company  or any  such  director,  officer,  controlling  person,  or
broker/dealer  or such other selling  Investor may become  subject to, under the
Securities  Act or  otherwise,  insofar  as  such  losses,  claims,  damages  or
liabilities  (or actions in respect  thereto) arise out of or are based upon any
untrue or  alleged  untrue  statement  of any  material  fact  contained  in the
Registration Statement or any such preliminary  prospectus,  relating thereto or
in any  amendments  or  supplements  to the  Registration  Statement or any such
preliminary  prospectus or final  prospectus,  or arise out of or are based upon
the omission or alleged omission to state therein a material fact required to be
or necessary to make the statements therein not misleading,  in each case to the
extent and only to the  extent  that such  untrue  statement  or alleged  untrue
statement  or  omission  or  alleged  omission  was  made  in  the  Registration
Statement, in any preliminary prospectus or final prospectus relating thereto or
in any  amendments  or  supplements  to the  Registration  Statement or any such
preliminary  prospectus or final prospectus,  in reliance upon and in conformity
with written information  furnished by the selling Investor expressly for use in
connection with the  Registration  Statement,  or any preliminary  prospectus or
final  prospectus;  and such selling  Investor will reimburse any legal or other
expenses  reasonably  incurred  by the  Company or any such  director,  officer,
controlling  person,  undertaker,  broker/dealer  or other  selling  Investor in
connection  with  investigating  or  defending  any  such  loss,  claim  damage,
liability or action,  provided,  however,  that the aggregate  liability of each
selling Investor  hereunder  (together with any liability for contribution under
Section 9(e)) shall be limited to the proceeds (net of  underwriting  discounts,
fees,  commissions  and any other  expenses  payable by such  selling  Investor)
received by such selling Investor from the sale of Registrable Shares covered by
the Registration Statement, and provided,  further,  however, that the indemnity
agreement  contained  in this  Section  9(b) shall not apply to amounts  paid in
settlement  of any  such  loss,  claim,  damage,  liability  or  action  if such
settlement is effected without the consent of those selling  Investor(s) against
which the  request  for  indemnity  is being made  (which  consent  shall not be
unreasonably withheld).

(c)  Promptly  after  receipt by an  indemnified  party under this  Section 9 of
notice of the  commencement  of any action,  such  indemnified  party will, if a
claim in respect thereof is to be made against any indemnifying party under this
Section 9, notify the indemnified  party in writing of the commencement  thereof
and the  indemnifying  party shall have the right to  participate in and, to the
extent the indemnifying party desires, jointly with any other indemnifying party
similarly  noticed,  to assume at its expense the defense  thereof  with counsel
mutually  satisfactory  to the  indemnifying  parties  with the  consent  of the
indemnified party which consent will not be unreasonably  withheld,  conditioned
or delayed.  In the event that the indemnifying  party assumes any such defense,
the  indemnified  party may participate in such defense with its own counsel and
at its own expense (unless the  indemnifying  party and indemnified  party shall
have  mutually  agreed to the  retention of such counsel or the named parties in
any such  proceeding  include both the  indemnifying  party and the  indemnified
party  and  representation  of  both  parties  by  the  same  counsel  would  be
inappropriate  due to actual or potential  differing  interests  between  them),
provided, however, that the counsel for the indemnifying party shall act as lead
counsel in all matters  pertaining  to such defense or  settlement of such claim
and the indemnifying party shall only pay for such indemnified  party's expenses
for the  period  prior to the date of its  participation  on such  defense.  The
failure to notify an indemnifying party promptly of the commencement of any such
action  will  not  relieve  it  from  any  liability  which  it may  have to any
indemnified  party under this  Section 9 (except to the extent that such failure
materially and adversely affects the indemnifying party's ability to defend such
action) or from any liability otherwise than under this Section 9.
<PAGE> 57

(d)  Notwithstanding  anything to the contrary herein,  the  indemnifying  party
shall  not be  entitled  to  settle  any  claim,  suit or  proceeding  unless in
connection with such settlement the indemnified  party receives an unconditional
release with respect to the subject matter of such claim, suit or proceeding and
such  settlement  does not contain  any  admission  of fault by the  indemnified
party.

(e) If the  indemnification  provided for in this Section 9 is unavailable to or
insufficient to hold harmless an indemnified  party under  subsection (a) or (b)
above in respect of any losses,  claims,  damages,  liabilities  or expenses (or
actions or  proceedings  in respect  thereof)  referred  to  therein,  then each
indemnifying  party  shall  contribute  to the  amount  paid or  payable by such
indemnified party as a result of such losses,  claims,  damages,  liabilities or
expenses (or actions in respect thereof) in such proportion as is appropriate to
reflect the relative  fault of the Company on the one hand and the  Investors on
the other in connection  with the statements or omissions or other matters which
resulted in such losses, claims, damages, liabilities or expenses (or actions in
respect thereof),  as well as any other relevant equitable  considerations.  The
relative  fault shall be determined by reference to, among other things,  in the
case of an untrue statement, whether the untrue statement relates to information
supplied  by the  Company  on the one hand or an  Investor  on the other and the
parties'  relative intent,  knowledge,  access to information and opportunity to
correct or prevent such untrue  statement.  The Company and the Investors  agree
that it  would  not be just  and  equitable  if  contribution  pursuant  to this
subsection  (e) were  determined by pro rata  allocation  (even if the Investors
were  treated  as one  entity  for  such  purpose)  or by any  other  method  of
allocation  which  does not  take  into  account  the  equitable  considerations
referred  to above in this  subsection  (e).  The  amount  paid or payable by an
indemnified party as a result of the losses,  claims, damages or liabilities (or
actions in respect  thereof)  referred to above in this  subsection (e) shall be
deemed  to  include  any legal or other  expenses  reasonably  incurred  by such
indemnified party in connection with  investigating or defending any such action
or claim.  Notwithstanding  the provisions of this  subsection  (e), no Investor
shall be required to  contribute  any amount in excess of the  proceeds  (net of
underwriting discounts, fees, commissions and any other expenses payable by such
selling Investor) received by such selling Investor from the sale of Registrable
Shares  covered by the  Registration  Statement.  No person guilty of fraudulent
misrepresentation  (within the meaning of Section 11(f) of the  Securities  Act)
shall be  entitled  to  contribution  from any person who was not guilty of such
fraudulent  misrepresentation.  The Investors' obligations in this subsection to
contribute  are several in  proportion to their sales of  Registrable  Shares to
which such loss relates and not joint.

10.  REPORTS  UNDER THE  EXCHANGE  ACT.  With a view to making  available to the
Investors  the benefits of Rule 144 and any other rule or  regulation of the SEC
that may at any time permit the  Investors to sell the  Purchased  Shares to the
public without registration,  the Company agrees to use reasonable best efforts:
(i) to make and keep public information available, as those terms are understood
and  defined  in the  General  Instructions  to Form S-3,  or any  successor  or
substitute  form,  and in Rule 144, (ii) to file with the SEC in a timely manner
all reports and other documents  required to be filed by an issuer of securities
registered  under the  Securities  Act or the Exchange Act, (iii) as long as any
Investor owns any Purchased  Shares,  to furnish in writing upon such Investor's
request  a  written  statement  by the  Company  that it has  complied  with the
reporting  requirements  of Rule 144 and of the  Securities Act and the Exchange
Act,  and to  furnish  to such  Investor  a copy of the most  recent  annual  or
quarterly  report of the Company,  and such other reports and documents so filed
by the Company as may be  reasonably  requested in availing such Investor of any
rule or  regulation  of the SEC  permitting  the  selling of any such  Purchased
Shares without registration and (iv) undertake any additional actions reasonably
necessary to maintain the availability of the Registration  Statement or the use
of Rule 144.
<PAGE> 58

11. DEFERRAL. Notwithstanding anything in this Agreement to the contrary, if the
Company  shall  furnish to the  selling  Investors a  certificate  signed by the
President of the Company  stating that the Board of Directors of the Company has
made  the good  faith  determination,  based  on  advice  of  counsel,  (i) that
continued  use by  the  selling  Investors  of the  Registration  Statement  for
purposes of effecting  offers or sales of Registrable  Shares  pursuant  thereto
would  require,   under  the  Securities  Act,   premature   disclosure  in  the
Registration  Statement  (or  the  prospectus  relating  thereto)  of  material,
nonpublic  information  concerning the Company, its business or prospects or any
proposed material  transaction  involving the Company,  (ii) that such premature
disclosure would be materially adverse to the Company, its business or prospects
or  any  such  proposed  material  transaction  or  would  make  the  successful
consummation by the Company of any such material transaction  significantly less
likely  and (iii)  that it is  therefore  essential  to  suspend  the use by the
Investors of such Registration  Statement (and the prospectus  relating thereto)
for  purposes  of  effecting  offers  or sales of  Registrable  Shares  pursuant
thereto,  then  the  right  of the  selling  Investors  to use the  Registration
Statement (and the prospectus relating thereto) for purposes of effecting offers
or sales of Registrable  Shares pursuant thereto shall be suspended for a period
(the  "Suspension  Period")  of not more than 60 days for any single  suspension
event after delivery by the Company of the certificate referred to above in this
Section 11; provided, however that the Company shall not utilize this right more
than twice in any  12-month  period and not sooner than 30 days after the end of
the prior  Suspension  Period;  and provided,  further that the right of selling
Investors  shall not be  suspended  for more than an aggregate of 90 days in any
12-month period. During the Suspension Period, none of the Investors shall offer
or sell any Registrable  Shares pursuant to or in reliance upon the Registration
Statement (or the prospectus relating thereto).

12.  TRANSFER OF REGISTRATION  RIGHTS.  None of the rights of any Investor under
this  Agreement  shall be  transferred or assigned to any person unless (i) such
person is a Qualifying Holder (as defined below), and (ii) such person agrees to
become a party to,  and bound by,  all of the  terms  and  conditions  of,  this
Agreement by duly  executing  and  delivering  to the Company an  instrument  of
adherence in the form  prescribed  by the Company.  For purposes of this Section
12, the term "Qualifying  Holder" shall mean, with respect to any Investor,  (i)
any partner  thereof,  (ii) any  affiliate  of such  Investor or a partner of an
affiliate or any corporation,  partnership,  limited  liability company or other
entity or person controlling,  controlled by, or under common control with, such
Investor or any partner thereof,  or (iii) any other direct transferee from such
Investor  of at  least  25% of  those  Registrable  Shares  held or that  may be
acquired  by such  Investor.  None of the  rights  of any  Investor  under  this
Agreement  shall be  transferred or assigned to any Person  (including,  without
limitation,  a Qualifying Holder) that acquires  Registrable Shares in the event
that and to the extent that such  Person is eligible to resell such  Registrable
Shares pursuant to Rule 144(k) of the Securities Act.

13.      ENTIRE AGREEMENT.  This Agreement constitutes and contains the entire
         ----------------   agreement and understanding of the parties with

respect to the subject matter hereof,  and it also  supersedes any and all prior
negotiations,  correspondence,  agreements or understandings with respect to the
subject matter hereof.

14.      MISCELLANEOUS.
         -------------

(a) This Agreement may not be amended, modified or terminated,  and no rights or
provisions  may be waived,  except  with the  written  consent  of the  Majority
Holders  and  the  Company;  provided  that  no  such  amendment,  modification,
termination   or  waiver  shall  affect  any  Investor  or  group  of  Investors
differently from all Investors, except with the written consent of such Investor
or group of Investors.
<PAGE> 59

(b) This Agreement shall be governed by and construed and enforced in accordance
with the laws of the  Commonwealth of  Massachusetts,  and shall be binding upon
and inure to the  benefit  of the  parties  hereto and their  respective  heirs,
personal  representatives,  successors  or assigns,  provided that the terms and
conditions  of Section 12 hereof are  satisfied.  This  Agreement  shall also be
binding upon and inure to the benefit of any  transferee of any of the Purchased
Shares,  provided  that the terms  and  conditions  of  Section  12  hereof  are
satisfied. Notwithstanding anything in this Agreement to the contrary, if at any
time  any  Investor  shall  cease  to own any  Registrable  Shares,  all of such
Investor's rights under this Agreement shall immediately terminate.

(c) (i) Any notices, reports or other correspondence  (hereinafter  collectively
referred to as  "correspondence")  required or permitted  to be given  hereunder
shall be sent by courier  (overnight or same day) or fax or delivered by hand to
the party to whom such  correspondence  is  required  or  permitted  to be given
hereunder.  The date of  giving  any  notice  shall  be the  date of its  actual
receipt.

(ii)  All correspondence to the Company shall be addressed as follows:
      ----------------------------------------------------------------

                           BioSphere Medical, Inc.
                           1050 Hingham Street
                           Rockland, MA 02370
                           Attention:  President
                           Fax:  781-681-5093

                           with a copy to:
                           Hale and Dorr LLP
                           60 State Street
                           Boston, MA 02109
                           Attention:  John H. Chory, Esq.
                           Fax: 617-526-5000

(iii) All  correspondence  to any Investor shall be sent to such Investor at the
address set forth in Exhibit A.

                           with a copy to:
                           Morrison & Foerster
                           1290 Avenue of the Americas
                           New York, New York  10104-0012
                           Attention:  Jeff Marcus, Esq.
                           Fax:  212-468-7900

(d)      Any entity may change the address to which correspondence to it is to
be addressed by notification as provided for herein.

(e) The  parties  acknowledge  and agree that in the event of any breach of this
Agreement,  remedies at law may be  inadequate,  and each of the parties  hereto
shall be entitled to seek specific  performance of the  obligations of the other
parties  hereto and such  appropriate  injunctive  relief as may be granted by a
court of competent jurisdiction.

(f) This  Agreement  may be  executed in a number of  counterparts,  an of which
together shall for all purposes  constitute  one  Agreement,  binding on all the
parties  hereto  notwithstanding  that all such parties have not signed the same
counterpart.
<PAGE> 60

15.  ADDITIONAL  INVESTORS.  The parties agree and acknowledge  that the Company
may, in its sole  discretion  and without  obtaining  the consent of any Initial
Investor,  issue and sell  additional  shares of its Common Stock to one or more
additional  purchasers pursuant to the Stock Purchase Agreement and that in such
event,  such  additional  purchasers  will become  parties to this  Agreement by
signing a signature page hereto.  Upon execution of such  signature  page,  such
parties shall be deemed "Initial Investors" and "Investors"  hereunder and shall
be deemed to be added to  EXHIBIT A hereto,  and the  shares of Common  Stock so
purchased  shall be deemed to be  "Purchased  Shares" and  "Registrable  Shares"
hereunder.

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


                                                     BIOSPHERE MEDICAL, INC.

                                                     By:      /S/John Carnuccio
                                                              ------------------
                                                     Name:    John Carnuccio
                                                     Title:   President


<PAGE> 61



                            PURCHASER SIGNATURE PAGE

     The undersigned Purchaser hereby executes the Registration Rights Agreement
with BioSphere  Medical,  Inc. and hereby  authorizes  this signature page to be
attached  to a  counterpart  of such  documents  executed  by a duly  authorized
officer of BioSphere Medical, Inc.




                                                Name of Purchaser - PLEASE
                                                PRINT OR TYPE

                                                [SIGN HERE]:

                                                 By:  /S/
                                                    ----------------------------

                                                 Title:
                                                       -------------------------

                                                 Address:
                                                         -----------------------






<PAGE> 62
                                                                     Exhibit A

                      Schedule of Investors - First Closing
<TABLE>
<CAPTION>
                                           Number of Shares
Name and Address of Purchaser                  Purchased
-------------------------------------     -----------------
<S>                                       <C>
Pequod Investments, L.P.
450 Park Avenue, 28th Floor
New York, NY 10022 TIN: 13-3746010                49,800

Pequod International, LTD
450 Park Avenue, 28th Floor
New York, NY 10022 TIN: 13-3746010                20,100

Richter Investment Corp.
450 Park Avenue
New York, NY 10022 TIN: 13-3514730                 5,000

Domain Public Equity Partners L.P.
One Palmer Square, Suite 515
Princeton, NJ 08542 TIN: 22-3714573               80,000

United Capital Management, Inc.
410 17th Street, # 1705
Denver, CO 80202 TIN: 84-1441847                 181,818

Rudman Partners, L.P.
540 Madison Avenue
New York, NY 10022 TIN: 13-3367586                90,909

Summer Hill Partners L.P.
6800 Cintas Blvd.
Mason, OH 45040 TIN: 31-1196101                   45,455

Sepracor Inc.
111 Locke Drive
Marlborough, MA 01752
TIN:  222536587                                  454,545

Pharma w/Health
c/o Merlin BioMed Group
230 Park Avenue, Suite 928
New York, NY 10169
TIN:  None                                       136,363

Castle Creek Healthcare Partners LLC
c/o Castle Creek Partners LLC
77 West Wacker Drive, Suite 4040
Chicago, IL 60601
TIN:  52-2137654                                  72,728

CCL Fund LLC
c/o Castle Creek Life Science
Partners LLC
77 West Wacker Drive, Suite 4040
Chicago, IL 60601
TIN:  36-4334064                                  18,182

                                          -----------------
TOTALS:                                        1,154,900
                                          =================
</TABLE>

<PAGE> 63
                   Schedule of Investors - Additional Closing
<TABLE>
<CAPTION>
                                           Number of Shares
Name and Address of Purchaser                  Purchased
-------------------------------------     -----------------

<S>                                       <C>
Teton Partners
c/o Noble Partners, L.P.
101 Federal Street
Boston, MA 02110 TIN: 04-3116395                  50,000

Jane Macrae
c/o Roger Amonica
Morgan Stanley Dean Witter
Four Headquarters Plaza
North Tower, 10th Floor
P.O. Box 1903
Morristown, NJ 07962
TIN:  59-6802915                                  10,000

                                          -----------------
TOTALS:                                           60,000
                                          =================
</TABLE>