Document:

Exhibit 10.01

                            STOCK PURCHASE AGREEMENT
                                    Between
                      HUMAN BIOSYSTEMS ("TARGET COMPANY")
                                     and
                          LANGLEY PARK INVESTMENTS PLC
                                 July 29, 2004

 TABLE OF CONTENTS

ARTICLE I	CERTAIN DEFINITIONS	                                 1
1.1	Certain Definitions	                                         1

ARTICLE II	PURCHASE AND SALE OF SHARES	                         4
2.1	Purchase and Sale; Purchase Price	                         4
2.2	Execution and Delivery of Documents; The Closing                 5

ARTICLE III	 REPRESENTATIONS AND WARRANTIES	                         5
3.1	Representations, Warranties and Agreements of the Target Company 5
3.2	Representations and Warranties of Langley	                 8

ARTICLE IV	OTHER AGREEMENTS OF THE PARTIES                  	11
4.1	Manner of Offering	                                        11
4.2	Notice of Certain Events                                 	12
4.3	Blue Sky Laws	                                                12
4.4	Integration	                                                12
4.5	Furnishing of Rule 144(c) Materials                         	12
4.6	Solicitation Materials	                                        12
4.7	Listing of Common Stock                                    	13
4.8	Indemnification	                                                13
4.9	Sale of Langley Shares	                                        15
4.10	Lock Up by Langley	                                        15
4.11	London Stock Exchange                                    	15

ARTICLE V	MISCELLANEOUS	                                        15
5.1	Fees and Expenses.	                                        15
5.2	Entire Agreement	                                        15
5.3	Notices.	                                                15
5.4	Amendments; Waivers	                                        16
5.5	Headings	                                                16
5.6	Successors and Assigns.                                  	16
5.7	No Third Party Beneficiaries                              	17
5.8	Governing Law; Venue; Service of Process.                   	17
5.9	Survival.	                                                17
5.10	Counterpart Signatures.	                                        17
5.11	Publicity.	                                                17
5.12	Severability.	                                                17
5.13	Limitation of Remedies.                                   	17

LIST OF SCHEDULES:

Schedule 3.1(a)	Subsidiaries
Schedule 3.1(c)	Capitalization and Registration Rights
Schedule 3.1(d)	Equity and Equity Equivalent Securities
Schedule 3.1(e)	Conflicts
Schedule 3.1(f)	Consents and Approvals
Schedule 3.1(g) 	Litigation
Schedule 3.1(h)	Defaults and Violations

LIST OF EXHIBITS:

Exhibit A	Escrow Agreement
Exhibit B	Officer's Certificate

THIS STOCK PURCHASE AGREEMENT (this "Agreement") is made and entered into as of
July 29, 2004, between  Human BioSystems, a corporation organized and existing
under the laws of the State ofCalifornia (the "Target Company"), and Langley
Park Investments PLC, a corporation organized under the laws of England and
Wales with its offices at 30 Farringdon Street, London EC4A 4HJ  ( "Langley").

WHEREAS, subject to the terms and conditions set forth in this Agreement, the
Target Company desires to issue and sell to Langley and Langley desires to
acquire from the Target Company the shares of the Target Company's common stock,
no par value (the "Common Stock") for the Total Purchase Price (as defined
herein).  The consideration to be paid by Langley for the Common Stock shall be
subject to certain downside price protection (the "Downside Price Protection")
provided in Section 2 of the Escrow Agreement.

IN CONSIDERATION of the mutual covenants contained in this Agreement, the Target
Company and Langley agree as follows:

                                   ARTICLE I
                              CERTAIN DEFINITIONS

1.1  Certain Definitions.  As used in this Agreement, and unless the context
requires a different meaning, the following terms have the meanings indicated:

  "Affiliate" means, with respect to any Person, any Person that, directly or
  indirectly, controls, is controlled by or is under common control with such
  Person.  For the purposes of this definition, "control" (including, with
  correlative meanings, the terms "controlled by" and "under common control
  with") shall mean the possession, directly or indirectly, of the power to
  direct or cause the direction of the management and policies of such Person,
  whether through the ownership of voting securities or by contract or
  otherwise.

  "Agreement" shall have the meaning set forth in the introductory paragraph of
  this Agreement.

  "Attorney-in-Fact" means Gottbetter & Partners, LLP, 488 Madison Avenue, 12
  Floor, New York, NY 10022; Tel: 212-400-6900; Fax: 212-400-6901.

  "Business Day" means any day except Saturday, Sunday, any day which shall be a
  legal holiday or a day on which banking institutions in the State of New York
  are authorized or required by law or other government actions to close.

  "Change of Control" means the acquisition, directly or indirectly, by any
  Person of ownership of, or the power to direct the exercise of voting power
  with respect to, a majority of the issued and outstanding voting shares of the
  Target Company.

  "Closing" shall have the meaning set forth in Section 2.2(a) hereof.

  "Closing Bid Price" shall mean the closing bid price for a share of Common
  Stock on such date on the OTCBB (or such other exchange, market, or other
  system that the Common Stock is then traded on), as reported on Bloomberg,
  L.P. (or similar organization or agency succeeding to its functions of
  reporting prices).

  "Closing Date" shall have the meaning set forth in Section 2.2(a) hereof.

                                   -1-

  "Closing Price" shall be the closing bid price of the Common Stock on the day
  of Closing.

  "Common Stock" shall have the meaning in the recital.

  "Consideration Stock" shall have the meaning set forth in Section 2.1(a)
  hereof.

  "Control Person" shall have the meaning set forth in Section 4.8(a) hereof.

  "Default" means any event or condition which constitutes an Event of Default
  or which with the giving of notice or lapse of time or both would, unless
  cured or waived, become an Event of Default.

  "Disclosure Documents" means the Target Company's reports filed under the
  Exchange Act with the SEC.

  "Downside Price Protection" shall have the meaning in the recital.

  "Escrow Agent" means Gottbetter & Partners, LLP, 488 Madison Avenue, 12 Floor,
  New York, NY 10022; Tel: 212-400-6900; Fax: 212-400-6901.

  "Escrow Agreement" means the escrow agreement, dated the date hereof, by and
  among the Target Company, Langley and the Escrow Agent annexed hereto as
  Exhibit A.

  [not used here].

  "Exchange Act" means the Securities Exchange Act of 1934, as amended.

  "Execution Date" means the date of this Agreement first written above.

  "Indemnified Party" shall have the meaning set forth in Section 4.8(b) hereof.

  "Indemnifying Party" shall have the meaning set forth in Section 4.8(b)
  hereof.

  "G&P" means Gottbetter & Partners, LLP.

  "Langley" shall have the meaning in the introductory paragraph.

                                   -2-

  "Langley Consideration Shares" shall have the meaning in Section 2.1(c)
  hereof.

  "Langley Escrow Shares" means the Langley Consideration Shares deposited into
  escrow by the Target Company under the terms of the Escrow Agreement in
  Exhibit A.

  "Langley Protection Shares" means the Langley Escrow Shares that the Target
  Company is required to sell to Langley under the terms of the Escrow Agreement
  in Exhibit A.

  "Langley Shares" shall mean ordinary shares of 1.0p each in Langley.

  "Losses" shall have the meaning set forth in Section 4.8(a) hereof.

  "Material" shall mean having a financial consequence in excess of $25,000.

  "Material Adverse Effect" shall have the meaning set forth in Section 3.1(a).

  "NASD" means the National Association of Securities Dealers, Inc.

  "Nasdaq" shall mean the Nasdaq Stock Market, Inc.

  "OTCBB" shall mean the NASD over-the counter Bulletin Board .

  "Per Share Market Value" of the Common Stock means on any particular date (a)
  the last sale price of shares of Common Stock on such date or, if no such sale
  takes place on such date, the last sale price on the most recent prior date,
  in each case as officially reported on the principal national securities
  exchange on which the Common Stock is then listed or admitted to trading, or
  (b) if the Common Stock is not then listed or admitted to trading on any
  national securities exchange, the closing bid price per share as reported by
  Nasdaq, or (c) if the Common Stock is not then listed or admitted to trading
  on the Nasdaq, the closing bid price per share of the Common Stock on such
  date as reported on the OTCBB or if there is no such price on such date, then
  the last bid price on the date nearest preceding such date, or (d) if the
  Common Stock is not quoted on the OTCBB, the closing bid price for a share of
  Common Stock on such date in the over-the-counter market as reported by the
  Pinksheets LLC (or similar organization or agency succeeding to its functions
  of reporting prices) or if there is no such price on such date, then the last
  bid price on the date nearest preceding such date, or (e) if the Common Stock
  is no longer publicly traded, the fair market value of a share of the Common
  Stock as determined by an appraiser selected in good faith by Langley and the
  Target Company.

  "Person" means an individual or a corporation, partnership, trust,
  incorporated or unincorporated association, joint venture, limited liability
  company, joint stock company, government (or an agency or political
  subdivision thereof) or other entity of any kind.

  "Proceeding" means an action, claim, suit, investigation or proceeding
  (including, without limitation, an investigation or partial proceeding, such
  as a deposition), whether commenced or threatened.

                                -3-

  "Reporting Issuer" means a company that is subject to the reporting
  requirements of Section 13 or 15(d) of the Exchange Act.

  "Required Approvals" shall have the meaning set forth in Section 3.1(f).

  "Securities" means the Common Stock and stock of any other class into which
  such shares may hereafter have been reclassified or changed.

  "SEC" means the Securities and Exchange Commission.

  "Securities Act" means the Securities Act of 1933, as amended.

  "Subsidiaries" shall have the meaning set forth in Section 3.1(a).

  "Target Company" shall have the meaning set forth in the introductory
  paragraph.

  "Total Purchase Price" shall have the meaning  set forth in Section 2.1(b).

  "Trading Day" means (a) a day on which the Common Stock is quoted on Nasdaq,
  the OTCBB or the principal stock exchange on which the Common Stock has been
  listed, or (b) if the Common Stock is not quoted on Nasdaq, the OTCBB or any
  stock exchange, a day on which the Common Stock is quoted in the over-the-
  counter market, as reported by the Pinksheets LLC (or any similar organization
  or agency succeeding its functions of reporting prices).

  "Transaction Documents" means this Agreement and all exhibits and schedules
  hereto and all other documents, instruments and writings required pursuant to
  this Agreement.

  "U.S." means the United States.

                                   ARTICLE II
                          PURCHASE AND SALE OF SHARES

     2.1 Purchase and Sale; Purchase Price.

        (a) Subject to the terms and conditions set forth herein, the Target
	Company shall issue and sell and Langley shall purchase seven million
	(7,000,000) shares of the Target Company's Common Stock (the
	"Consideration Stock").

        (b) The total purchase price (the "Total Purchase Price") shall be the
	number of shares of Consideration Stock multiplied by the average of the
	Closing Bid Price per share of Common Stock during the ten (10) Trading
	Days immediately preceding July 30, 2004.

        (c) The Total Purchase Price shall be paid by delivery to the Target
	Company of the number of Langley Shares (the "Langley Consideration
	Shares") equal to the Total Purchase Price divided by the conversion
	rate of the British Pound Sterling to purchase US Dollars determined
	below.   The Langley Shares shall have a value of U.K. $1 per share.
	The number of Langley Shares to be issued will be based on the
	conversion rate of the British Pound Sterling to the US Dollar in effect
	as of the close of business on July 30, 2004 , as quoted by Coutts & Co.
	as the commercial rate it gives to purchase US Dollars. For example, if
	the effective conversion rate is $1.80/U.K. $ 1 and the Total Purchase
	Price is $8,000,000, then the number of Langley Shares the Target
	Company will receive shall equal $8,000,000/$1.80, or 4,444,444 Langley
	Shares.  The Langley Consideration Shares shall be subject to the
	"Downside Price Protection" provided in Section 2 of the Escrow
	Agreement.

                                    -4-

   2.2	Execution and Delivery of Documents; The Closing.

       (a) The Closing of the purchase and sale of the shares of Consideration
       Stock (the "Closing") shall take place within sixty (60) days from the
       date hereof (the "Closing Date").  On the Closing Date,

          (i)   the Target Company shall execute and deliver to the Escrow Agent
	  a certificate in the name of Langley representing shares of
	  Consideration Stock;

          (ii)  the Target Company shall execute and deliver to Langley a
	  certificate of its President, in the form of Exhibit B annexed hereto,
	  certifying that attached thereto is a copy of resolutions duly adopted
	  by the Board of Directors of the Target Company authorizing the Target
	  Company to execute and deliver the Transaction Documents and to enter
	  into the transactions contemplated thereby;

          (iii)	the Target Company, Langley and the Escrow Agent shall execute
	  and deliver to each other the Escrow Agreement;

          (iv) 	Langley shall deliver the Langley Consideration Shares to the
	  Escrow Agent; and

          (v)   the Target Company shall wire the monies owed to G&P pursuant to
	  Section 5.1 hereof for legal fees with the following wire
	  instructions:

	                   Citibank, N.A. 488 Madison Avenue New York, NY ABA
			   Routing No.: 021000089 Account Name: Gottbetter &
			   Partners, LLP Account No. 49061322 Reference:
			   [Target Company]

                                   -5-

                                  ARTICLE III
                         REPRESENTATIONS AND WARRANTIES

   3.1	Representations, Warranties and Agreements of the Target Company.  The
   Target Company hereby makes the following representations and warranties to
   Langley, all of which shall survive the Closing:

       (a) Organization and Qualification.  The Target Company is a corporation,
       duly incorporated, validly existing and in good standing under the laws
       of the State of California, with the requisite corporate power and
       authority to own and use its properties and assets and to carry on its
       business as currently conducted.  The Target Company has no subsidiaries
       other than as set forth on Schedule 3.1(a) attached hereto (collectively,
       the "Subsidiaries").  Each of the Subsidiaries is a corporation, duly
       incorporated, validly existing and in good standing under the laws of the
       jurisdiction of its incorporation, with the full corporate power and
       authority to own and use its properties and assets and to carry on its
       business as currently conducted.  Each of the Target Company and the
       Subsidiaries is duly qualified to do business and is in good standing as
       a foreign corporation in each jurisdiction in which the nature of the
       business conducted or property owned by it makes such qualification
       necessary, except where the failure to be so qualified or in good
       standing, as the case may be, would not, individually or in the
       aggregate, have a material adverse effect on the results of operations,
       assets, prospects, or financial condition of the Target Company and the
       Subsidiaries, taken as a whole (a "Material Adverse Effect").

       (b) Authorization, Enforcement.  The Target Company has the requisite
       corporate power and authority to enter into and to consummate the
       transactions contemplated hereby and by each other Transaction Document
       and to otherwise to carry out its obligations hereunder and thereunder.
       The execution and delivery of this Agreement and each of the other
       Transaction Documents by the Target Company and the consummation by it of
       the transactions contemplated hereby and thereby has been duly authorized
       by all necessary action on the part of the Target Company.  Each of this
       Agreement and each of the other Transaction Documents has been or will be
       duly executed by the Target Company and when delivered in accordance with
       the terms hereof or thereof will constitute the valid and binding
       obligation of the Target Company enforceable against the Target Company
       in accordance with its terms, except as such enforceability may be
       limited by applicable bankruptcy, insolvency, reorganization, moratorium,
       liquidation or similar laws relating to, or affecting generally the
       enforcement of, creditors' rights and remedies or by other equitable
       principles of general application.

       (c) Capitalization.  The authorized, issued and outstanding capital stock
       of the Company is set forth on Schedule 3.1(c).  No shares of Common
       Stock are entitled to preemptive or similar rights, nor is any holder of
       the Common Stock entitled to preemptive or similar rights arising out of
       any agreement or understanding with the Target Company by virtue of this
       Agreement.  Except as disclosed in Schedule 3.1(c), there are no
       outstanding options, warrants, script, rights to subscribe to,
       registration rights, calls or commitments of any character whatsoever
       relating to securities, rights or obligations convertible into or
       exchangeable for, or giving any person any right to subscribe for or
       acquire, any shares of Common Stock, or contracts, commitments,
       understandings, or arrangements by which the Target Company or any
       Subsidiary is or may become bound to issue additional shares of Common
       Stock, or securities or rights convertible or exchangeable into shares of
       Common Stock.  Neither the Target Company nor any Subsidiary is in
       violation of any of the provisions of its Articles of Incorporation,
       bylaws or other charter documents.

                                      -6-

       (d) Issuance of Securities.  The shares of Consideration Stock have been
       duly and validly authorized for issuance, offer and sale pursuant to this
       Agreement and, when issued and delivered as provided hereunder against
       payment in accordance with the terms hereof, shall be valid and binding
       obligations of the Target Company enforceable in accordance with their
       respective terms.

       (e) No Conflicts.  The execution, delivery and performance of this
       Agreement and the other Transaction Documents by the Target Company and
       the consummation by the Target Company of the transactions contemplated
       hereby and thereby do not and will not (i) conflict with or violate any
       provision of its Articles of Incorporation or bylaws (each as amended
       through the date hereof) or (ii) be subject to obtaining any consents
       except those referred to in Section 3.1(f), conflict with, or constitute
       a default (or an event which with notice or lapse of time or both would
       become a default) under, or give to others any rights of termination,
       amendment, acceleration or cancellation of, any agreement, indenture or
       instrument to which the Target Company is a party, or (iii) result in a
       violation of any law, rule, regulation, order, judgment, injunction,
       decree or other restriction of any court or governmental authority to
       which the Target Company or its Subsidiaries is subject (including, but
       not limited to, those of other countries and the federal and state
       securities laws and regulations), or by which any property or asset of
       the Target Company or its Subsidiaries is bound or affected, except in
       the case of clause (ii), such conflicts, defaults, terminations,
       amendments, accelerations, cancellations and violations as would not,
       individually or in the aggregate, have a Material Adverse Effect.  The
       business of the Target Company and its Subsidiaries is not being
       conducted in violation of any law, ordinance or regulation of any
       governmental authority.

       (f) Consents and Approvals.  Except as specifically set forth in Schedule
       3.1(f), neither the Target Company nor any Subsidiary is required to
       obtain any consent, waiver, authorization or order of, or make any filing
       or registration with, any court or other federal, state, local or other
       governmental authority or other Person in connection with the execution,
       delivery and performance by the Target Company of this Agreement and each
       of the other Transaction Documents (together with the consents, waivers,
       authorizations, orders, notices and filings referred to in Schedule
       3.1(f), the "Required Approvals").

       (g) Litigation; Proceedings.  Except as specifically disclosed in
       Schedule 3.1(g), there is no action, suit, notice of violation,
       proceeding or investigation pending or, to the best knowledge of the
       Target Company, threatened against or affecting the Target Company or any
       of its Subsidiaries or any of their respective properties before or by
       any court, governmental or administrative agency or regulatory authority
       (federal, state, county, local or foreign) which (i) relates to or
       challenges the legality, validity or enforceability of any of the
       Transaction Documents or the shares of Consideration Stock, (ii) could,
       individually or in the aggregate, have a Material Adverse Effect or (iii)
       could, individually or in the aggregate, materially impair the ability of
       the Target Company to perform fully on a timely basis its obligations
       under the Transaction Documents.

                                     -7-

       (h) No Default or Violation.  Except as set forth in Schedule 3.1(h)
       hereto, neither the Target Company nor any Subsidiary (i) is in default
       under or in violation of any indenture, loan or credit agreement or any
       other agreement or instrument to which it is a party or by which it or
       any of its properties is bound, except such conflicts or defaults as do
       not have a Material Adverse Effect, (ii) is in violation of any order of
       any court, arbitrator or governmental body, except for such violations as
       do not have a Material Adverse Effect, or (iii) is in violation of any
       statute, rule or regulation of any governmental authority which could
       (individually or in the aggregate) (a) adversely affect the legality,
       validity or enforceability of this Agreement, (b) have a Material
       Adverse Effect or (c) adversely impair the Target Company's ability or
       obligation to perform fully on a timely basis its obligations under this
       Agreement.

       (i) Disclosure Documents.  The Disclosure Documents are accurate in all
       material respects and do not contain any untrue statement of material
       fact or omit to state any material fact necessary in order to make the
       statements made therein, in light of the circumstances under which they
       were made, not misleading.

       (j) Non-Registered Offering.  Neither the Target Company nor any Person
       acting on its behalf has taken or will take any action (including,
       without limitation, any offering of any securities of the Target Company
       under circumstances which would require the integration of such offering
       with the offering of the Securities under the Securities Act) which might
       subject the offering, issuance or sale of the Securities to the
       registration requirements of Section 5 of the Securities Act.

       (k) Placing Agent.  The Target Company accepts and agrees that Dungarvon
       Associates, Inc. ("Dungarvon") is acting for Langley and does not regard
       any person other than Langley as its customer in relation to this
       Agreement, and that it has not made any recommendation to the Target
       Company, in relation to this Agreement and is not advising the Target
       Company, with regard to the suitability or merits of the Langley Shares
       and in particular Dungarvon has no duties or responsibilities to the
       Target Company for the best execution of the transaction contemplated by
       this Agreement.

       (l) Private Placement Representations. The Target Company (i) has
       received and carefully reviewed such information and documentation
       relating to Langley that the Target Company has requested, including,
       without limitation, Langley's Confidential Private Offering Memorandum
       dated June 17, 2004; (ii)  has had a reasonable opportunity to ask
       questions of and receive answers from Langley concerning the Langley
       Shares, and all such questions, if any, have been answered to the full
       satisfaction of the Target Company; (iii) has such knowledge and
       expertise in financial and business matters that it is capable of
       evaluating the merits and risks involved in an investment in the Langley
       Shares; (iii) understands that Langley has determined that the exemption
       from the registration provisions of the Securities Act of 1933, as
       amended (the "Securities Act"), provided by  Section 4(2) of the
       Securities Act is applicable to the offer and sale of the Langley Shares,
       based, in part, upon the representations, warranties and agreements made
       by the Target Company herein; and (iv) except as provided herein and in
       the Private Placement Memorandum, dated June 17, 2004, no representations
       or warranties have been made to the Target Company by Langley or any
       agent, employee or affiliate of Langley and in entering into this
       transaction the Target Company is not relying upon any information, other
       than the results of independent investigation by the Target Company.

                                      -8-

Langley acknowledges and agrees that the Target Company makes no representation
or warranty with respect to the transactions contemplated hereby other than
those specifically set forth in Section 3.1 hereof.

   3.2	Representations and Warranties of Langley.  Langley hereby represents
   and warrants to the Target Company as follows:

       (a) Organization; Authority.  Langley is a corporation, duly organized,
       validly existing and in good standing under the laws of the jurisdiction
       of its formation with the requisite power and authority to enter into and
       to consummate the transactions contemplated hereby and by the other
       Transaction Documents and otherwise to carry out its obligations
       hereunder and thereunder.  The acquisition of the shares of Consideration
       Stock to be purchased by Langley hereunder has been duly authorized by
       all necessary action on the part of Langley.  This Agreement has been
       duly executed and delivered by Langley and constitutes the valid and
       legally binding obligation of Langley, enforceable against it in
       accordance with its terms, except as such enforceability may be limited
       by applicable bankruptcy, insolvency, reorganization, moratorium or
       similar laws relating to, or affecting generally the enforcement of,
       creditors rights and remedies or by other general principles of equity.

       (b) Investment Intent.  Langley is acquiring the shares of Consideration
       Stock to be purchased by it hereunder, for its own account for investment
       purposes only and not with a view to or for distributing or reselling
       such shares of Consideration Stock, or any part thereof or interest
       therein, without prejudice, however, to Langley's right, subject to the
       provisions of this Agreement, at all times to sell or otherwise dispose
       of all or any part of such shares of Consideration Stock in compliance
       with applicable federal and state securities laws.

       (c) Experience of Langley.  Langley, either alone or together with its
       representatives, has such knowledge, sophistication and experience in
       business and financial matters so as to be capable of evaluating the
       merits and risks of an investment in the shares of Consideration Stock to
       be acquired by it hereunder, and has so evaluated the merits and risks of
       such investment.

                                   -9-

       (d) Ability of Langley to Bear Risk of Investment.  Langley is able to
       bear the economic risk of an investment in the Securities to be acquired
       by it hereunder and, at the present time, is able to afford a complete
       loss of such investment.

       (e) Access to Information.  Langley acknowledges that it has been
       afforded (i) the opportunity to ask such questions as it has deemed
       necessary of, and to receive answers from, representatives of the Target
       Company concerning the terms and conditions of the Securities offered
       hereunder and the merits and risks of investing in such securities; (ii)
       access to information about the Target Company and the Target Company's
       financial condition, results of operations, business, properties,
       management and prospects sufficient to enable it to evaluate its
       investment in the Securities; and (iii) the opportunity to obtain such
       additional information which the Target Company possesses or can acquire
       without unreasonable effort or expense that is necessary to make an
       informed investment decision with respect to the investment and to verify
       the accuracy and completeness of the information that it has received
       about the Target Company.

       (f) Reliance.  Langley understands and acknowledges that (i) the shares
       of Consideration Stock being offered and sold to it hereunder are being
       offered and sold without registration under the Securities Act in a
       private placement that is exempt from the registration provisions of the
       Securities Act under Section 4(2) of the Securities Act and (ii) the
       availability of such exemption depends in part on, and that the Target
       Company will rely upon the accuracy and truthfulness of, the foregoing
       representations and Langley hereby consents to such reliance.

       (g) Regulation S.  Langley understand and acknowledge that (A) the shares
       of Consideration Stock have not been registered under the Securities Act,
       are being sold in reliance upon an exemption from registration afforded
       by Regulation S; and that such shares of Consideration Stock have not
       been registered with any state securities commission or authority; (B)
       pursuant to the requirements of Regulation S, the shares of Consideration
       Stock may not be transferred, sold or otherwise exchanged unless in
       compliance with the provisions of Regulation S and/or pursuant to
       registration under the Securities Act, or pursuant to an available
       exemption hereunder; and (C) Langley is under no obligation to register
       the shares of Consideration Stock under the Securities Act or any state
       securities law, or to take any action to make any exemption from any such
       registration provisions available.

	   Langley is not a U.S. person and is not acquiring the shares of
	   Consideration Stock for the account of any U.S. person; (B) no
	   director or executive officer of Langley is a national or citizen of
	   the United States; and (C) it is not otherwise deemed to be a "U.S.
	   Person" within the meaning of Regulation S.

	   Langley was not formed specifically for the purpose of acquiring the
	   shares of Consideration Stock purchased pursuant to this Agreement.

	   Langley is purchasing the shares of Consideration Stock for its own
	   account and risk and not for the account or benefit of a U.S. Person
	   as defined in Regulation S and no other person has any interest in or
	   participation in the shares of Consideration Stock or any right,
	   option, security interest, pledge or other interest in or to the
	   shares of Consideration Stock.  Langley understands, acknowledges and
	   agrees that it must bear the economic risk of its investment in the
	   shares of Consideration Stock for an indefinite period of time and
	   that prior to any such offer or sale, the Target Company may require,
	   as a condition to effecting a transfer of the shares of Consideration
	   Stock, an opinion of counsel, acceptable to the Target Company, as to
	   the registration or exemption therefrom under the Securities Act and
	   any state securities acts, if applicable.

                                      -10-

	   Langley will, after the expiration of the Restricted Period, as set
	   forth under Regulation S Rule 903(b)(3)(iii)(A), offer, sell, pledge
	   or otherwise transfer the shares of Consideration Stock only in
	   accordance with Regulation S, or pursuant to an available exemption
	   under the Securities Act and, in any case, in accordance with
	   applicable state securities laws.  The transactions contemplated by
	   this Agreement have neither been pre-arranged with a purchaser who is
	   in the U.S. or who is a U.S. Person, nor are they part of a plan or
	   scheme to evade the registration provisions of the United States
	   federal securities laws.

	   The offer leading to the sale evidenced hereby was made in an
	   "offshore transaction."  For purposes of Regulation S, Langley
	   understands that an "offshore transaction" as defined under
	   Regulation S is any offer or sale not made to a person in the United
	   States and either (A) at the time the buy order is originated, the
	   purchaser is outside the United States, or the seller or any person
	   acting on his behalf reasonably believes that the purchaser is
	   outside the United States; or (B) for purposes of (1) Rule 903 of
	   Regulation S, the transaction is executed in, or on or through a
	   physical trading floor of an established foreign exchange that is
	   located outside the United States or (2) Rule 904 of Regulation S,
	   the transaction is executed in, on or through the facilities of a
	   designated offshore securities market, and neither the seller nor any
	   person acting on its behalf knows that the transaction has been
	   prearranged with a buyer in the U.S.

	   Neither Langley nor any affiliate or any person acting on Langley's
	   behalf, has made or is aware of any "directed selling efforts" in the
	   United States, which is defined in Regulation S to be any activity
	   undertaken for the purpose of, or that could reasonably be expected
	   to have the effect of, conditioning the market in the United States
	   for any of the shares of Consideration Stock being purchased hereby.

	   Langley understands that the Target Company is the seller of the
	   shares of Consideration Stock which are the subject of this
	   Agreement, and that, for purpose of Regulation S, a "distributor" is
	   any underwriter, dealer or other person who participates, pursuant to
	   a contractual arrangement, in the distribution of securities offered
	   or sold in reliance on Regulation S and that an "affiliate" is any
	   partner, officer, director or any person directly or indirectly
	   controlling, controlled by or under common control with any person in
	   question.  Langley agrees that Langley will not, during the
	   Restricted Period set forth under Rule 903(b)(iii)(A), act as a
	   distributor, either directly or though any affiliate, nor shall it
	   sell, transfer, hypothecate or otherwise convey the shares of
	   Consideration Stock other than to a non-U.S. Person.

	   Langley acknowledges that the shares of Consideration Stock will bear
	   a legend in substantially the following form:

	                           -11-

THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE BEEN OFFERED AND SOLD IN AN
"OFFSHORE TRANSACTION" IN RELIANCE UPON REGULATION S AS PROMULGATED BY THE
SECURITIES AND EXCHANGE  COMMISSION. ACCORDINGLY, THE SECURITIES REPRESENTED BY
THIS CERTIFICATE HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933 (THE
"SECURITIES ACT") AND MAY NOT BE TRANSFERRED OTHER THAN IN ACCORDANCE WITH
REGULATION S, PURSUANT TO REGISTRATION UNDER THE SECURITIES ACT, OR PURSUANT TO
AN AVAILABLE EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT, THE
AVAILABILITY OF WHICH IS TO BE ESTABLISHED TO THE SATISFACTION OF THE COMPANY.
THE SECURITIES REPRESENTED BY THIS CERTIFICATE CANNOT BE THE SUBJECT OF HEDGING
TRANSACTIONS UNLESS SUCH TRANSACTIONS ARE CONDUCTED IN COMPLIANCE WITH THE
SECURITIES ACT.

The Target Company acknowledges and agrees that Langley makes no representations
or warranties with respect to the transactions contemplated hereby other than
those specifically set forth in this Section 3.2.

                                   ARTICLE IV
                        OTHER AGREEMENTS OF THE PARTIES

    4.1	Manner of Offering.  The Securities are being issued pursuant to section
    4(2) of the Securities Act and Regulation S thereunder.  The Langley
    Consideration Shares are being issued pursuant to section 4(2) of the
    Securities Act and Rule 506 of Regulation D thereunder.

    4.2	Notice of Certain Events.  The Target Company shall, on a continuing
    basis, (i) advise Langley promptly after obtaining knowledge of, and, if
    requested by Langley, confirm such advice in writing, of (A) the issuance by
    any state securities commission of any stop order suspending the
    qualification or exemption from qualification of the shares of Consideration
    Stock, for offering or sale in any jurisdiction, or the initiation of any
    proceeding for such purpose by any state securities commission or other
    regulatory authority, or (B) any event that makes any statement of a
    material fact made by the Target Company in Section 3.1 or in the Disclosure
    Documents untrue or that requires the making of any additions to or changes
    in Section 3.1  or in the Disclosure Documents in order to make the
    statements therein, in the light of the circumstances under which they are
    made, not misleading, (ii) use its best efforts to prevent the issuance of
    any stop order or order suspending the qualification or exemption from
    qualification of the Securities under any state securities or Blue Sky laws,
    and (iii) if at any time any state securities commission or other regulatory
    authority shall issue an order suspending the qualification or exemption
    from qualification of the Securities under any such laws, and use its best
    efforts to obtain the withdrawal or lifting of such order at the earliest
    possible time.

                                   -12-

   4.3	Blue Sky Laws.  The Target Company agrees that it will execute all
    necessary documents and pay all necessary state filing or notice fees to
    enable the Target Company to sell the Securities to Langley.

    4.4	Integration.  The Target Company shall not and shall use its best
    efforts to ensure that no Affiliate shall sell, offer for sale or solicit
    offers to buy or otherwise negotiate in respect of any security (as defined
    in Section 2 of the Securities Act) that would be integrated with the offer
    or sale of the Securities in a manner that would require the registration
    under the Securities Act of the sale of the Securities to Langley.

    4.5	Furnishing of Rule 144(c) Materials.  The Target Company shall, for so
    long as any of the Securities remain outstanding and during any period in
    which the Target Company is not subject to Section 13 or 15(d) of the
    Exchange Act, make available to any registered holder of the Securities
    ("Holder" or "Holders") in connection with any sale thereof and any
    prospective purchaser of such Securities from such Person, such information
    in accordance with Rule 144(c) promulgated under the Securities Act as is
    required to sell the Securities under Rule 144 promulgated under the
    Securities Act.

    4.6	Solicitation Materials.  The Target Company shall not (i) distribute any
    offering materials in connection with the offering and sale of the shares of
    Consideration Stock other than the Disclosure Documents and any amendments
    and supplements thereto prepared in compliance herewith or (ii) solicit any
    offer to buy or sell the shares of Consideration Stock by means of any form
    of general solicitation or advertising.

    4.7	Listing of Common Stock.  If the Common Stock is or shall become listed
    on the OTCBB or on another exchange, the Target Company shall (a) use its
    best efforts to maintain the listing of its Common Stock on the OTCBB or
    such other exchange on which the Common Stock is then listed until two years
    from the date hereof, and (b) shall provide to Langley evidence of such
    listing.

    4.8	Indemnification.

     (a) Indemnification.

        (i)   The Target Company shall, notwithstanding termination of this
	Agreement and without limitation as to time, indemnify and hold harmless
	Langley and its officers, directors, agents, employees and affiliates,
	each Person who controls or Langley (within the meaning of Section 15 of
	the Securities Act or Section 20 of the Exchange Act) (each such Person,
	a "Control Person") and the officers, directors, agents,  employees and
	affiliates of each such Control Person, to the fullest extent permitted
	by applicable law, from and against any and all losses, claims, damages,
	liabilities, costs (including, without limitation, costs of preparation
	and attorneys' fees) and expenses (collectively, "Losses"), as incurred,
	arising out of, or relating to, a breach or breaches of any
	representation, warranty, covenant or agreement by the Target Company
	under this Agreement or any other Transaction Document.

                                    -13-

        (ii)  Langley shall, notwithstanding termination of this Agreement and
	without limitation as to time, indemnify and hold harmless the Target
	Company, its officers, directors, agents and employees, each Control
	Person and the officers, directors, agents and employees of each Control
	Person, to the fullest extent permitted by application law, from and
	against any and all Losses, as incurred, arising out of, or relating to,
	a breach or breaches of any representation, warranty, covenant or
	agreement by Langley under this Agreement or the other Transaction
	Documents.

        (iii) The Target Company and Langley acknowledge that in the SEC's
	opinion, directors, officers and persons controlling a company subject
	to the Securities Act can not be indemnified for liabilities arising
	under the Securities Act by such company.

     (b) Conduct of Indemnification Proceedings.  If any Proceeding shall be
     brought or asserted against any Person entitled to indemnity hereunder (an
     "Indemnified Party"), such Indemnified Party promptly shall notify the
     Person from whom indemnity is sought (the "Indemnifying Party") in writing,
     and the Indemnifying Party shall assume the defense thereof, including the
     employment of counsel reasonably satisfactory to the Indemnified Party and
     the payment of all fees and expenses incurred in connection with defense
     thereof; provided, that the failure of any Indemnified Party to give such
     notice shall not relieve the Indemnifying Party of its obligations or
     liabilities pursuant to this Agreement, except (and only) to the extent
     that it shall be finally determined by a court of competent jurisdiction
     (which determination is not subject to appeal or further review) that such
     failure shall have proximately and materially adversely prejudiced the
     Indemnifying Party.

	 An Indemnified Party shall have the right to employ separate counsel in
	 any such Proceeding and to participate in the defense thereof, but the
	 fees and expenses of such counsel shall be at the expense of such
	 Indemnified Party or Parties unless: (1) the Indemnifying Party has
	 agreed to pay such fees and expenses; or (2) the Indemnifying Party
	 shall have failed promptly to assume the defense of such Proceeding and
	 to employ counsel reasonably satisfactory to such Indemnified Party in
	 any such Proceeding; or (3) the named parties to any such Proceeding
	 (including any impleaded parties) include both such Indemnified Party
	 and the Indemnifying Party, and such Indemnified Party shall have been
	 advised by counsel that a conflict of interest is likely to exist if
	 the same counsel were to represent such Indemnified Party and the
	 Indemnifying Party (in which case, if such Indemnified Party notifies
	 the Indemnifying Party in writing that it elects to employ separate
	 counsel at the expense of the Indemnifying Party, the Indemnifying
	 Party shall not have the right to assume the defense of the claim
	 against the Indemnified Party but will retain the right to control the
	 overall Proceedings out of which the claim arose and such counsel
	 employed by the Indemnified Party shall be at the expense of the
	 Indemnifying Party).  The Indemnifying Party shall not be liable for
	 any settlement of any such Proceeding effected without its written
	 consent, which consent shall not be unreasonably withheld.  No
	 Indemnifying Party shall, without the prior written consent of the
	 Indemnified Party, effect any settlement of any pending Proceeding in
	 respect of which any Indemnified Party is a party, unless such
	 settlement includes an unconditional release of such Indemnified Party
	 from all liability on claims that are the subject matter of such
	 Proceeding.

	 All fees and expenses of the Indemnified Party to which the Indemnified
	 Party is entitled hereunder (including reasonable fees and expenses to
	 the extent incurred in connection with investigating or preparing to
	 defend such Proceeding in a manner not inconsistent with this Section)
	 shall be paid to the Indemnified Party, as incurred, within ten (10)
	 Business Days of written notice thereof to the Indemnifying Party.

	                              -14-

	 No right of indemnification under this Section shall be available as to
	 a particular Indemnified Party if the Indemnifying Party obtains a non-
	 appealable final judicial determination that such Losses arise solely
	 out of the negligence or bad faith of such Indemnified Party in
	 performing the obligations of such Indemnified Party under this
	 Agreement or a breach by such Indemnified Party of its obligations
	 under this Agreement.

    (c)  Contribution.  If a claim for indemnification under this Section is
    unavailable to an Indemnified Party or is insufficient to hold such
    Indemnified Party harmless for any Losses in respect of which this Section
    would apply by its terms (other than by reason of exceptions provided in
    this Section), then each Indemnifying Party, in lieu of indemnifying such
    Indemnified Party, shall contribute to the amount paid or payable by such
    Indemnified Party as a result of such Losses in such proportion as is
    appropriate to reflect the relative benefits received by the Indemnifying
    Party on the one hand and the Indemnified Party on the other and the
    relative fault of the Indemnifying Party and Indemnified Party in connection
    with the actions or omissions that resulted in such Losses as well as any
    other relevant equitable considerations.   The relative fault of such
    Indemnifying Party and Indemnified Party shall be determined by reference
    to, among other things, whether there was a judicial determination that such
    Losses arise in part out of the negligence or bad faith of the Indemnified
    Party in performing the obligations of such Indemnified Party under this
    Agreement or the Indemnified Party's breach of its obligations under this
    Agreement.  The amount paid or payable by a party as a result of any Losses
    shall be deemed to include any attorneys' or other fees or expenses incurred
    by such party in connection with any Proceeding to the extent such party
    would have been indemnified for such fees or expenses if the indemnification
    provided for in this Section was available to such party.

    (d)	Non-Exclusivity.  The indemnity and contribution agreements contained in
    this Section are in addition to any obligation or liability that the
    Indemnifying Parties may have to the Indemnified Parties.

   4.9	Sale of Langley Consideration Shares. Langley shall assist the Target
   Company in setting up and maintaining a trading account at a registered
   broker in the United Kingdom to facilitate the sale of the Langley
   Consideration Shares. Broker's commissions in the trading account shall not
   exceed one half percent (0.5%).

   4.10	Lock Up by Langley. Langley shall not sell, transfer or assign all or
   any of the shares of Consideration Stock for a period of two (2) years
   following the Closing, without the written consent of the Target Company,
   which consent may be withheld in the Target Company's sole discretion.

                                  -15-

                                   ARTICLE V
                                 MISCELLANEOUS

   5.1	Fees and Expenses.  Except as set forth in this Agreement, each party
   shall pay the fees and expenses of its advisers, counsel, accountants and
   other experts, if any, and all other expenses incurred by such party incident
   to the negotiation, preparation, execution, delivery and performance of this
   Agreement.  The Target Company shall pay all stamp and other taxes and duties
   levied in connection with the issuance of the shares of Consideration Stock
   pursuant hereto.  Langley shall be responsible for any taxes payable by
   Langley that may arise as a result of the investment hereunder or the
   transactions contemplated by this Agreement or any other Transaction
   Document.  The Target Company agrees to pay Langley's counsel a total of
   $7,500 for legal fees associated with the transactions contemplated by this
   Agreement at Closing. The Target Company shall pay all costs, expenses, fees
   and all taxes incident to and in connection with:  (A) the issuance and
   delivery of the Securities, (B) the exemption from registration of the
   Securities for offer and sale to Langley under the securities or Blue Sky
   laws of the applicable jurisdictions, and (C) the preparation of certificates
   for the Securities (including, without limitation, printing and engraving
   thereof), and (D) all fees and expenses of counsel and accountants of the
   Target Company.

   5.2	Entire Agreement  This Agreement, together with all of the Exhibits
   annexed hereto, and any other Transaction Document contains the entire
   understanding of the parties with respect to the subject matter hereof and
   supersede all prior agreements and understandings, oral or written, with
   respect to such matters.  This Agreement shall be deemed to have been drafted
   and negotiated by both parties hereto and no presumptions as to
   interpretation, construction or enforceability shall be made by or against
   either party in such regard.

   5.3	Notices.  Any notice or other communication required or permitted to be
   given hereunder shall be in writing and shall be deemed to have been duly
   given upon facsimile transmission (with written transmission confirmation
   report) at the number designated below (if delivered on a Business Day during
   normal business hours where such notice is to be received), or the first
   Business Day following such delivery (if delivered other than on a Business
   Day during normal business hours where such notice is to be received)
   whichever shall first occur.  The addresses for such communications shall be:

If to the Target Company:	 Human BioSystems
                                 Attn:  Harry Masuda
                                 President and CEO
	                         1127 Harker Avenue
	                         Palo Alto, CA  94301
                                 Tel:   (650) 323-0943
                                 Fax:   (650 ) 327-8658

With copies to:	                 Silicon Valley Law Group
		                 Attn:  Cathryn S. Gawne, Esq.
		                 25 Metro Drive, Suite 600
		                 San Jose, CA  95110
                                 Tel:  (408) 573-5700
                                 Fax:  (408) 573-5701

If to Langley:             	Langley Park Investments PLC
		                30 Farringdon Street
		                London EC4A 4HJ
		                Attn: Harry Pearl
		                Tel: 44.207.569.0044
		                Fax: 44.207.724.0090

With copies to:	               Gottbetter & Partners, LLP
                               488 Madison Avenue, 12th Floor
                               New York, NY 10022
                               Attn:  Adam S. Gottbetter, Esq.
                               Tel:  (212) 400-6900
                               Fax:  (212) 400-6901

                                -16-

or such other address as may be designated hereafter by notice given pursuant to
the terms of this Section 5.3.

   5.4	Amendments; Waivers.  No provision of this Agreement may be waived or
   amended except in a written instrument signed, in the case of an amendment,
   by both the Target Company and Langley, or, in the case of a waiver, by the
   party against whom enforcement of any such waiver is sought.  No waiver of
   any default with respect to any provision, condition or requirement of this
   Agreement shall be deemed to be a continuing waiver in the future or a waiver
   of any other provision, condition or requirement hereof, nor shall any delay
   or omission of either party to exercise any right hereunder in any manner
   impair the exercise of any such right accruing to it thereafter.

   5.5	Headings.  The headings herein are for convenience only, do not
   constitute a part of this Agreement and shall not be deemed to limit or
   affect any of the provisions hereof.

   5.6	Successors and Assigns. This Agreement shall be binding upon and inure
   to the benefit of the parties and their respective successors and permitted
   assigns.  The assignment by a party of this Agreement or any rights hereunder
   shall not affect the obligations of such party under this Agreement.

   5.7	No Third Party Beneficiaries.  This Agreement is intended for the
   benefit of the parties hereto and their respective permitted successors and
   assigns and is not for the benefit of, nor may any provision hereof be
   enforced by, any other person.

   5.8	Governing Law; Venue; Service of Process.  The parties hereto
   acknowledge that the transactions contemplated by this Agreement and the
   exhibits hereto bear a reasonable relation to the State of New York.  The
   parties hereto agree that the internal laws of the State of New York shall
   govern this Agreement and the exhibits hereto, including, but not limited to,
   all issues related to usury.  Any action to enforce the terms of this
   Agreement or any of its exhibits, or any other Transaction Document shall be
   brought exclusively in the state and/or federal courts situated in the County
   and State of New York.  If and only if New York declines jurisdiction within
   the State of New York, such action shall be brought in the State and County
   where the Target Company's principal place of business is situated.  Service
   of process in any action by Langley or the Target Company to enforce the
   terms of this Agreement may be made by serving a copy of the summons and
   complaint, in addition to any other relevant documents, by commercial
   overnight courier to the other party at its principal address set forth in
   this Agreement.

                                -17-

   5.9	Survival.  The representations and warranties of the Target Company and
   Langley contained in Article III and the agreements and covenants of the
   parties contained in Article IV and this Article V shall survive the Closing.

   5.10	Counterpart Signatures.  This Agreement may be executed in two or more
   counterparts, all of which when taken together shall be considered one and
   the same agreement and shall become effective when counterparts have been
   signed by each party and delivered to the other party, it being understood
   that both parties need not sign the same counterpart.  In the event that any
   signature is delivered by facsimile transmission, such signature shall create
   a valid and binding obligation of the party executing (or on whose behalf
   such signature is executed) the same with the same force and effect as if
   such facsimile signature page were an original thereof.

   5.11	Publicity.  The Target Company and Langley shall consult with each other
   in issuing any press releases or otherwise making public statements with
   respect to the transactions contemplated hereby and neither party shall issue
   any such press release or otherwise make any such public statement without
   the prior written consent of the other, which consent shall not be
   unreasonably withheld or delayed, unless counsel for the disclosing party
   deems such public statement to be required by applicable federal and/or state
   securities laws.  Except as otherwise required by applicable law or
   regulation, the Target Company will not disclose to any third party
   (excluding its legal counsel, accountants and representatives) the names of
   Langley.

   5.12	Severability.  In case any one or more of the provisions of this
   Agreement shall be invalid or unenforceable in any respect, the validity and
   enforceability of the remaining terms and provisions of this Agreement shall
   not in any way be affected or impaired thereby and the parties will attempt
   to agree upon a valid and enforceable provision which shall be a reasonable
   substitute therefore, and upon so agreeing, shall incorporate such substitute
   provision in this Agreement.

   5.13	Limitation of Remedies.  With respect to claims by the Target Company or
   any person acting by or through the Target Company, or by Langley or any
   person acting through Langley, for remedies at law or at equity relating to
   or arising out of a breach of this Agreement, liability, if any, shall, in no
   event, include loss of profits or incidental, indirect, exemplary, punitive,
   special or consequential damages of any kind.

[   SIGNATURE PAGE FOLLOWS   ]

                                        -18-

IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be duly
executed as of the date first indicated above.

				Target Company:

				Human BioSystems

				By: /s/ Harry Masuda
				    --------------------
				Name:  Harry Masuda
				Title: President and CEO

				Langley:
     			        Dungarvon Associates, Inc. on behalf of
				Langley Park Investments Plc.
				By: /s/Rufus Pearl
				     -------------------
				Name: Rufus Pearl
				Title: Administrative Director

                                    -19-

NOTE: EXHIBIT 'A' and EXHIBIT 'B' OF THIS AGREEMENT
      HAVE BEEN FILED AS EXHIBIT 10.02Exhibit 10.02

                           ESCROW AGREEMENT

	ESCROW AGREEMENT (this "Agreement"), dated as of July 29, 2004, by and
	between  Human BioSystems, a California corporation with its principal
	place of business at 1127 Harker Avenue, Palo Alto, CA  94301 (the
	"Target Company");  Gottbetter & Partners, LLP with its principal place
	of business at 488 Madison Avenue, New York, NY 10022 (the "Escrow
	Agent"); and Langley Park Investments Plc, a corporation organized under
	the laws of England and Wales with its offices at 30 Farringdon Street,
	London EC4A 4HJ ("Langley").

                                    Recitals

		A.	Simultaneously with the execution of this Agreement,
		Langley and the Target Company entered into a Stock Purchase
		Agreement (the "Stock Purchase Agreement"), dated as of the date
		hereof and incorporated herein by reference, pursuant to which
		the Target Company has agreed that the Consideration Stock, and
		Langley has agreed that the Langley Consideration Shares, shall
		be deposited into escrow pursuant to this Agreement, including
		fifty percent (50%) of the Langley Consideration Shares to be
		deposited into escrow as Downside Price Protection (the "Langley
		Escrow Shares").

		B.	The Escrow Agent is willing to act as escrow agent
		pursuant to the terms of this Agreement with respect to the
		purchase of the shares of Consideration Stock.

		C.	All capitalized terms used but not defined herein shall
		have the meanings ascribed thereto in the Stock Purchase
		Agreement.

	NOW, THEREFORE, IT IS AGREED:

		1.	Deposit into Escrow.    At Closing, the Target Company
		shall (i) deposit the Langley Consideration Shares with the
		Escrow Agent, (ii) deliver blank stock powers (the "Stock
		Powers") for the Langley Escrow Shares to the Escrow Agent and
		(iii) deposit the Consideration Stock with the Escrow Agent.
		The Escrow Agent shall hold the Langley Consideration Shares,
		the Consideration Stock and the Stock Powers in escrow when
		delivered.

	2.	Terms of Escrow.  (a)  If the Market Value of the Common Stock
	two years after Closing is less than the Closing Price, the Target
	Company shall sell to Langley the number of Langley Escrow Shares (the
	"Langley Protection Shares") equal to (a) the Langley Consideration
	Shares multiplied by (b) the Percentage Decrease, at a purchase price of
	1p per Langley Consideration Share (the "Escrow Purchase Price").  The
	"Percentage Decrease" shall be equal to 1 - Market Value/the Closing
	Price. "Market Value" shall be the average of the ten (10) closing bid
	prices per share of the Common Stock during the ten (10) trading days
	immediately preceding the two year anniversary of the Closing.

 Within three (3) Business Days of the two year anniversary of the Closing,
 Langley shall (i) send a notice ("Sale Notice") to the Target Company and the
 Escrow Agent of the Langley Protection Shares to be sold by the Target Company
 to Langley, if any, and (ii) deposit the Escrow Purchase Price with the Escrow
 Agent, if necessary.  Within fourteen (14) Business Days of the Target
 Company's and the Escrow Agent's receipt of the Sale Notice and Escrow Agent's
 receipt of the Escrow Purchase Price, the Escrow Agent is authorized and
 directed (i) to pay the Escrow Purchase Price to the Target Company, if any,
 (ii) to deliver the Langley Protection Shares, if any, and the Stock Powers to
 Langley, (iii) to deliver the remaining Langley Escrow Shares, if any, to the
 Target Company, and (iv) to deliver the Stock Powers to the Target Company if
 the total number of Langley Protection Shares is zero.

(b)  	If at any time before September 30, 2004, the Langley Consideration
Shares are admitted for trading on the London Stock Exchange plc (the "London
Exchange"), the Escrow Agent is authorized and directed to distribute, within
fourteen (14) Business Days of such admittance, (i) the Consideration Stock to
Langley and (ii) fifty percent (50%) of the Langley Consideration Shares to the
Target Company.  If the Langley Consideration Shares are not admitted for
trading on the London Exchange by September 30, 2004, the Escrow Agent is
authorized and directed to distribute, no later than October 5, 2004, (i) the
Consideration Stock to the Target Company and (ii) the Langley Consideration
Shares to Langley.

	3.	Duties and Obligations of the Escrow Agent.

		(a)	The parties hereto agree that the duties and obligations
		of the Escrow Agent shall be only those obligations herein
		specifically provided and no other.  The Escrow Agent's duties
		are those of a depositary only, and the Escrow Agent shall incur
		no liability whatsoever, except as a direct result of its
		willful misconduct or gross negligence in the performance of its
		duties hereunder;

		(b)	The Escrow Agent may consult with counsel of its choice,
		and shall not be liable for any action taken, suffered or
		omitted to be taken by it in accordance with the advice of such
		counsel;

		(c)	The Escrow Agent shall not be bound in any way by the
		terms of any other agreement to which Langley and the Target
		Company are parties, whether or not the Escrow Agent has
		knowledge thereof, and the Escrow Agent shall not in any way be
		required to determine whether or not any other agreement has
		been complied with by Langley and the Target Company, or any
		other party thereto.  The Escrow Agent shall not be bound by any
		modification, amendment, termination, cancellation, rescission
		or supersession of this Agreement unless the same shall be in
		writing and signed jointly by Langley and the Target Company and
		agreed to in writing by the Escrow Agent;

		(d)	If the Escrow Agent shall be uncertain as to its duties
		or rights hereunder or shall receive instructions, claims or
		demands which, in its opinion, are in conflict with any of the
		provisions of this Agreement, the Escrow Agent shall be entitled
		to refrain from taking any action other than keeping safely the
		Consideration (as defined below) or taking certain action until
		the Escrow Agent is directed otherwise in writing jointly by
		Langley and the Target Company or by a final judgment of a court
		of competent jurisdiction;

		(e)	The Escrow Agent shall be fully protected in relying
		upon any written notice, demand, certificate or document which
		the Escrow Agent, in good faith, believes to be genuine.  The
		Escrow Agent shall not be responsible for the sufficiency or
		accuracy of the form, execution, validity or genuineness of
		documents or securities now or hereafter deposited hereunder or
		of any endorsement thereon, or for any lack of endorsement
		thereon, or for any description therein; nor shall the Escrow
		Agent be responsible or liable in any respect on account of the
		identity, authority or rights of the persons executing or
		delivering or purporting to execute or deliver any such
		document, security or endorsement;

		(f)	The Escrow Agent shall not be required to institute
		legal proceedings of any kind and shall not be required to
		defend any legal proceedings which may be instituted against it
		or in respect of the Consideration;

		(g)	If the Escrow Agent at any time, in its sole discretion,
		deems it necessary or advisable to relinquish custody of any of
		the Securities (to the extent delivered to the Escrow Agent
		pursuant hereto, the "Consideration"), it may do so by
		delivering the same to another Person that agrees to act as
		escrow agent hereunder and whose substitution for the Escrow
		Agent is agreed upon in writing by Langley and the Target
		Company; provided, however, that such successor Escrow Agent
		must be resident in the United States.  If no such escrow agent
		is selected within three (3) days after the Escrow Agent gives
		notice to Langley and the Target Company of the Escrow Agent's
		desire to so relinquish custody of the Consideration and resign
		as Escrow Agent, then the Escrow Agent may do so by delivering
		the Consideration to the clerk or other proper officer of a
		state or federal court of competent jurisdiction situate in the
		state and county of New York.  The fee of any court officer
		shall be borne  by the Target Company.  Upon such delivery, the
		Escrow Agent shall be discharged from any and all responsibility
		or liability with respect to the Consideration and this
		Agreement and each of the Target Company and Langley shall
		promptly pay all monies it may owe to the Escrow Agent for its
		services hereunder, including, but not limited to, reimbursement
		of its out-of-pocket expenses pursuant to paragraph (i) below;

		(h)	This Agreement shall not create any fiduciary duty on
		the Escrow Agent's part to Langley or the Target Company, nor
		disqualify the Escrow Agent from representing  either party
		hereto in any dispute with the other, including any dispute with
		respect to the Purchase Agreement or Debenture; provided,
		however, that in the event of such dispute, the Escrow Agent
		shall have the right to commence an interpleader action in any
		court of competent jurisdiction of the state of New York or of
		the United States located in the county and state of New York,
		deposit the Consideration with such court;

		(i)	The parties acknowledge and agree that the Escrow Agent
		is counsel to Langley.  The parties agree to, and agree not to
		object to, the Escrow Agent's engagement as Escrow Agent
		hereunder;

		(j)	Upon the full performance of this Agreement, the Escrow
		Agent shall be deemed released and discharged of any further
		obligations hereunder.

	4.	Indemnification.

		(a)	Langley hereby indemnifies and holds free and harmless
		the Escrow Agent from any and all losses, expenses, liabilities
		and damages (including but not limited to reasonable attorney's
		fees, and amounts paid in settlement) resulting from claims
		asserted by the Target Company against the Escrow Agent with
		respect to the performance of any of the provisions of this
		Agreement;

		(b)	The Target Company hereby indemnifies and holds free and
		harmless the Escrow Agent from any and all losses, expenses,
		liabilities and damages (including but not limited to reasonable
		attorney's fees, and amount paid in settlement) resulting from
		claims asserted by Langley against the Escrow Agent with respect
		to the performance of any of the provisions of this Agreement;

		(c)	Langley and the Target Company, jointly and severally,
		hereby indemnify and hold the Escrow Agent harmless from and
		against any and all losses, damages, taxes, liabilities and
		expenses that may be incurred by the Escrow Agent, arising out
		of or in connection with its acceptance of appointment as the
		Escrow Agent hereunder and/or the performance of its duties
		pursuant to this Agreement, the Purchase Agreement and the
		Securities, including, but not limited to, all legal costs and
		expenses of the Escrow Agent incurred defending itself against
		any claim or liability in connection with its performance
		hereunder, provided that the Escrow Agent shall not be entitled
		to any indemnity for any losses, damages, taxes, liabilities or
		expenses that directly result from its willful misconduct or
		gross negligence in its  performance as Escrow Agent hereunder

		(d)	In the event of any legal action or proceeding involving
		any of the parties to this Agreement which is brought to enforce
		or otherwise adjudicate any of the rights or obligations of the
		parties hereunder, the non-prevailing party or parties shall pay
		the legal fees of the prevailing party or parties and the legal
		fees, if any, of the Escrow Agent.

	5.	Miscellaneous.

		(a)	All notices, including Notices of Conversion and Notices
		of Exercise,  objections, requests, demands and other
		communications sent to any party hereunder shall be deemed duly
		given if (x) in writing and sent by facsimile transmission to
		the Person for whom intended if addressed to such Person at its
		facsimile number set forth below or such other facsimile number
		as such Person may designate by notice given pursuant to the
		terms of this Section 5 and (y) the sender has confirmation of
		transmission:

	(i)	If to the Target Company:	Human BioSystems
                                                Attn:  Harry Masuda
                                                President and CEO
                                                1127 Harker Avenue
                                                Palo Alto, CA 94301
						Tel:  (650) 323-0943
						Fax: (650) 327-8658

		(ii)	If to Langley:		Langley Park Investments PLC
						30 Farringdon Street
						London EC4A 4HJ
						Attn: Harry Pearl
						Tel: 44.207.569.0044
						Fax: 44.207.724.0090

		(iii)	If to the Escrow Agent:	Gottbetter & Partners, LLP
						488 Madison Ave.
						New York, New York 10022
						Attn:  Adam S. Gottbetter, Esq.
						Tel:  (212) 400-6900
						Fax:  (212) 400-6901

		(b)	This Agreement has been prepared, negotiated and
		delivered in the state of New York and shall be governed by and
		construed and enforced in accordance with the laws of the state
		of New York applicable to contracts entered into and performed
		entirely within New York, without giving effect to the
		principles of New York law relating to the conflict of laws.

		(c)	This Agreement may be executed in two or more
		counterparts, all of which when taken together shall be
		considered one and the same agreement and shall become effective
		when counterparts have been signed by each party and delivered
		to the other party, it being understood that both parties need
		not sign the same counterpart.  In the event that any signature
		is delivered by facsimile transmission, such signature shall
		create a valid and binding obligation of the party executing (or
		on whose behalf such signature is executed) the same with the
		same force and effect as if such facsimile signature page were
		an original thereof.

		(d)	This Agreement shall be binding upon and inure to the
		benefit of the parties and their successors and permitted
		assigns.  The assignment by a party of this Agreement or any
		rights hereunder shall not affect the obligations of such party
		under this Agreement.

	6.	Termination of Escrow.   The term of this Escrow Agreement shall
	begin upon the date hereof and shall continue until terminated upon the
	earlier to occur of (i) the Langley Escrow Shares are fully distributed
	or (ii) the written agreement of the parties to terminate this
	Agreement.  Upon the termination of this Escrow Agreement pursuant to
	subsection (ii), the Escrow Agent shall distribute any of the Langley
	Escrow Shares then held by it pursuant to the terms of the written
	agreement of the parties.

[ SIGNATURE PAGE FOLLOWS ]

	IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
	signed the day and year first above written.

     					The Target Company:

					Human BioSystems

					By: /s/ Harry Masuda
					   ____________________

					Name:Harry Masuda
					Title:President and CEO

					Langley:

					Dungarvon Associates, Inc. on behalf of
					Langley Park Investments Plc.

					By: /s/ Rufus Pearl
					    ______________________
					Name: Rufus Pearl
					Title:Administrative Director

					Escrow Agent:

					Gottbetter & Partners, LLP

					By:/s/Adam S. Gottbetter
					    ____________________________
					Name: Adam S Gottbetter
					Title: Managing Partner

EXHIBIT B

Human BioSystems

OFFICER'S CERTIFICATE

	I, Harry Masuda, being the President ofHuman BioSystems, a California
	corporation (the "Target Company"), pursuant to Section 2.2(a)(ii) of
	that certain Stock Purchase Agreement (the "Purchase Agreement"), dated
	as of July 29, 2004, by and between the Target Company and Langley Park
	Investments PLC, do hereby certify on behalf of the Target Company that
	attached hereto is a copy of the resolutions duly adopted by the Board
	of Directors of the Target Company authorizing the Target Company to
	execute and deliver the Transaction Documents, as such term is defined
	in the Purchase Agreement and to enter into the transactions
	contemplated thereby.

	IN WITNESS WHEREOF, I have executed this Officer's Certificate on behalf
of the Target Company this 29th day of July, 2004.

       Human BioSystems

       /s/Harry Masuda
      ___________________
    By:   Harry Masuda, President

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