Document:

<PAGE>

                                                                    Exhibit 10.2

                                 Schedule 4.3

I.  Authorized Capital

        A. Common Stock         30 million

        B. Preferred stock      1 million, of which approximately 15,000 have
                                been designated as Series A and of which 475,000
                                have been designated as Series C Convertible
                                Preferred Stock

II.  Outstanding Capital                       Equivalent Shares of Common Stock
                                               ---------------------------------

        A. Common Stock         approximately             19,000,000

        B. Stock Options        approximately              2,100,000

        C. Warrants             approximately              4,600,000<PAGE>
                                                                    Exhibit 10.3

                                 Schedule 4.16

                      PATENT STATUS OF BLSI TECHNOLOGIES

<TABLE>
<CAPTION>
Schedule 4.16
                              Application
             Year     Year      Serial      Patent
Technology   filed   issued     Number      Number     Title                                                      Comments
====================================================================================================================================
<S>          <C>     <C>         <C>      <C>          <C>                                                        <C>
Therafectin   N/A    1994         N/A      5,298,494   Monosaccharides having anti-proliferation and
                                                       anti-inflammatory activity,
                                                       compositions and uses thereof                              Use/manufacturing
------------------------------------------------------------------------------------------------------------------------------------
Altropane     N/A    1996         N/A      5,493,026   Substituted 2-Carboxyalkyl-3-(Flurophenyl)-8-
                                                       (3-Halopropen-2-YL) Nortropanes                            Composition
                                                       and their use as imaging for neurodegenerative disorders
------------------------------------------------------------------------------------------------------------------------------------
Troponin      N/A    1998         N/A      5,837,680   Pharmaceutical compositions comprising troponin subunits,
                                                       fragments and analogs thereof and methods of               Use
                                                       their use to inhibit angiogenesis
------------------------------------------------------------------------------------------------------------------------------------
AF-1          1997             08/916,642              Trophic factors for CNS Regeneration                       Use/composition
------------------------------------------------------------------------------------------------------------------------------------
Inosine       1997             08/921,902              Methods for Modulating the Axonal Outgrowth of CNS Neurons Use
------------------------------------------------------------------------------------------------------------------------------------
C-maf         1996             08/636,602              Methods and Compositions for Regulating T-cell subsets     Composition/Use
                                                       by Modulating Transcription Factor Activity
------------------------------------------------------------------------------------------------------------------------------------
</TABLE>
All patents have been filed and maintained in all major territories worldwide.
In the case of issued patents, these refer to US only. Foreign patents have not
yet been issued.<PAGE>

                                                                    EXHIBIT 10.4

                         REGISTRATION RIGHTS AGREEMENT
                         -----------------------------

          This Registration Rights Agreement (the "Agreement") is made and
entered into as of this 1st day of June, 2000 by and between Boston Life
Sciences, Inc., a Delaware corporation (the "Company"), and the "Investor" named
in that Purchase Agreement of even date herewith by and between the Company and
the Investor (the "Purchase Agreement").

          The parties hereby agree as follows:

          1.   Certain Definitions
               -------------------

               Terms not defined herein shall have the meanings defined in the
Purchase Agreement. As used in this Agreement, the following terms shall have
the following meanings:

               "Additional Registrable Securities" shall mean shares of Common
                ---------------------------------
Stock issuable or issued as a dividend or other distribution with respect to, or
in exchange for or in replacement of, such Common Stock.

               "Common Stock" shall mean the Company's Common Stock, par value
                ------------
$0.01 per share.

               "Investor" shall mean the purchaser identified in the Purchase
                --------
Agreement and any affiliate of the Investor who is a subsequent holder of any
Warrants or Registrable Securities.

               "Prospectus" shall mean the prospectus included in any
                ----------
Registration Statement, as amended or supplemented by any prospectus supplement,
with respect to the terms of the offering of any portion of the Registrable
Securities or Additional Registrable Securities covered by such Registration
Statement and by all other amendments and supplements to the prospectus,
including post-effective amendments and all material incorporated by reference
in such prospectus.

               "Register," "registered" and "registration" refer to a
                --------    ----------       ------------
registration made by preparing and filing a registration statement or similar
document in compliance with the 1933 Act (as defined below), and the declaration
or ordering of effectiveness of such registration statement or document.

               "Registrable Securities" shall mean (a) the shares of Common
                ----------------------
Stock issued and issuable to the Investor pursuant to the Purchase Agreement and
issuable upon the exercise of the Warrants, and (b) shares of Common Stock
issuable or issued as a dividend or other distribution with respect to, or in
exchange for or in replacement of, such Common Stock.
<PAGE>

               "Registration Statement" shall mean any registration statement
                ----------------------
filed under the 1933 Act of the Company that covers the resale of any of the
Registrable Securities or Additional Registrable Securities pursuant to the
provisions of this Agreement, amendments and supplements to such Registration
Statement, including post-effective amendments, all exhibits and all material
incorporated by reference in such Registration Statement.

               "SEC" means the U.S. Securities and Exchange Commission.
                ---

               "1933 Act" means the Securities Act of 1933, as amended, and the
                --------
rules and regulations promulgated thereunder.

               "1934 Act" means the Securities Exchange Act of 1934, as amended,
                --------
and the rules and regulations promulgated thereunder.

               "Warrants" mean the warrants to purchase shares of Common Stock
                --------
issued to the Investor pursuant to the Purchase Agreement, the form of which is
attached to the Purchase Agreement as Exhibit A.

          2.   Registration.
               ------------

               (a)  Registration Statements.
                    -----------------------

                    (i)  Registrable Securities. Promptly following the closing
                         ----------------------
of the purchase and sale of Common Stock and Warrants contemplated by the
Purchase Agreement (the "Closing Date") (but no later than thirty (30) days
after the Closing Date), the Company shall prepare and file with the SEC one
Registration Statement on Form S-3 (or, if Form S-3 is not then available to the
Company, on such form of registration statement as is then available to effect a
registration for resale of the Registrable Securities, subject to the Investor's
consent) covering the resale of the Registrable Securities in an amount equal to
the number of shares of Common Stock issued to the Investor on the Closing Date
plus the number of shares of Common Stock necessary to permit the exercise in
full of the Warrants. Such Registration Statement also shall cover, to the
extent allowable under the 1933 Act and the Rules promulgated thereunder
(including Rule 416), such indeterminate number of additional shares of Common
Stock resulting from stock splits, stock dividends or similar transactions with
respect to the Registrable Securities. The Registration Statement (and each
amendment or supplement thereto, and each request for acceleration of
effectiveness thereof) shall be provided in accordance with Section 3(c) to the
Investor and its counsel prior to its filing or other submission.

                                       2
<PAGE>

               (b)  Expenses.  The Company will pay all expenses associated with
                    --------
each registration, excluding discounts, commissions, fees of underwriters,
selling brokers, dealer managers or similar securities industry professionals.

               (c)  Effectiveness.
                    -------------

                    (i)  The Company shall use its best efforts to have each
Registration Statement declared effective as soon as practicable. If (A) the
Registration Statement covering Registrable Securities is not declared effective
by the SEC within ninety (90) days following the Closing Date, or with respect
to Registration Statement being subject to review by the SEC staff, within one
hundred thirty-four (134) days following the Closing Date as the case may be
(each, a "Registration Date"), (B) after a Registration Statement has been
declared effective by the SEC, sales cannot be made pursuant to such
Registration Statement (by reason of a stop order, or the Company's failure to
update the Registration Statement) but except as excused pursuant to
subparagraph (ii) below, or (C) the Common Stock generally or the Registrable
Securities specifically is not listed or included for quotation on the Nasdaq
National Market System, the Nasdaq Small Cap Market, the New York Stock Exchange
or the American Stock Exchange, then the Company will make pro-rata payments to
the Investor in the form of additional Common Stock, as liquidated damages and
not as a penalty, in an amount equal to 2% of the aggregate amount paid by the
Investor on the Closing Date to the Company for any month or pro rata for any
portion thereof following the Registration Date during which any of the events
described in (A) or (B) or (C) above occurs and is continuing (the "Blackout
Period"). The Blackout Period shall terminate upon (x) the effectiveness of the
applicable Registration Statement in the case of (A) and (B) above; (y) listing
or inclusion of the Common Stock on the Nasdaq National Market System, the
Nasdaq Small Cap Market, the New York Stock Exchange or the American Stock
Exchange in the case of (C) above; and (z) in the case of the events described
in (A) or (B) or (C) above, the earlier termination of the Registration Period
(as defined in Section 3(a) below). If the Blackout Period should continue for
three (3) months, then, at the option of the Investor, the Company shall issue

                                       3
<PAGE>

to the Investor Warrants to purchase a number of shares equal to 20% of the
number of shares of Common Stock then owned by the Investor, at an exercise
price equal to the lesser of the then Market Price (as that term is defined in
the Purchase Agreement) and the applicable Warrant Price (as that term is
defined in the Warrants) and otherwise in form and substance as the Warrants
issued pursuant to the Purchase Agreement. The Warrant issuance shall not be
exclusive of any other remedies available at law or in equity. The amounts
payable as liquidated damages pursuant to this paragraph shall be payable, at
the option of the Company, in lawful money of the United States or in shares of
Common Stock at the Market Price (as that term is defined in the Purchase
Agreement), and amounts payable as liquidated damages shall be paid monthly on
the last day of each month following the commencement of the Blackout Period
until the termination of the Blackout Period. Amounts payable as liquidated
damages hereunder shall cease when an Investor no longer holds Warrants or
Registrable Securities, or Additional Registrable Securities, as applicable.

                    (ii) For not more than thirty (30) consecutive trading days
(or not more than forty five (45) consecutive trading days if the event giving
rise thereto is an acquisition valued at in excess of $10,000,000 and the
consummation of which is required to be reported in a Current Report on Form 8-K
pursuant to Item 2 thereof), or for a total of not more than sixty (60) trading
days in any twelve (12) month period, the Company may delay the disclosure of
material non-public information concerning the Company, by terminating or
suspending effectiveness of any registration contemplated by this Section
containing such information, the disclosure of which at the time is not, in the
good faith opinion of the Company, in the best interests of the Company (an
"Allowed Delay"); provided, that the Company shall promptly (a) notify the
Investor in writing of the existence of (but in no event, without the prior
written consent of the Investor, shall the Company disclose to the Investor any
of the facts or circumstances regarding) material non-public information giving
rise to an Allowed Delay, and (b) advise the Investor in writing to cease all
sales under the Registration Statement until the end of the Allowed Delay.

               (d)  Underwritten Offering. If any offering pursuant to a
                    ---------------------
Registration Statement pursuant to Section 2(a) hereof involves an underwritten
offering, the Company shall have the right to select an investment banker and
manager to administer the offering, which investment banker or manager shall be
reasonably satisfactory to the Investor.

          3.   Company Obligations. The Company will use its best efforts to
               -------------------
effect the registration of the Registrable Securities and Additional Registrable
Securities in accordance with the terms hereof, and pursuant thereto the Company
will, as expeditiously as possible:

               (a)  use its best efforts to cause such Registration Statement to
become effective and to remain continuously effective for a period that will
terminate upon the earlier of the date on which (i) all Registrable Securities
or Additional Registrable Securities, as the case may be, covered by such
Registration Statement, as amended from time to time, have been sold (the
"Registration Period") or (ii) the Investor owns Common Stock having a market
value of less than $100,000;

                                       4
<PAGE>

               (b)  prepare and file with the SEC such amendments and post-
effective amendments to the Registration Statement and the Prospectus as may be
necessary to keep the Registration Statement effective for the period specified
in Section 3(a) and to comply with the provisions of the 1933 Act and the 1934
Act with respect to the distribution of all Registrable Securities and
Additional Registrable Securities; provided that, at least three (3) days prior
to the filing of a Registration Statement or Prospectus, or any amendments or
supplements thereto, the Company will furnish to the Investor copies of all
documents proposed to be filed, which documents will be subject to the
reasonable comments of the Investor;

               (c)  permit of counsel designated by the Investor to review each
Registration Statement and all amendments and supplements thereto no fewer than
three (3) days prior to their filing with the SEC and not file any document to
which such counsel reasonably objects on the basis that such document contains a
material misstatement or omission;

               (d)  furnish to the Investor and its legal counsel (i) promptly
after the same is prepared and publicly distributed, filed with the SEC, or
received by the Company, one copy of any Registration Statement and any
amendment thereto, each preliminary prospectus and Prospectus and each amendment
or supplement thereto, and each letter written by or on behalf of the Company to
the SEC or the staff of the SEC, and each item of correspondence from the SEC or
the staff of the SEC, in each case relating to such Registration Statement
(other than any portion of any thereof which contains information for which the
Company has sought confidential treatment), and (ii) such number of copies of a
Prospectus, including a preliminary prospectus, and all amendments and
supplements thereto and such other documents as such Investor may reasonably
request in order to facilitate the disposition of the Registrable Securities and
Additional Registrable Securities owned by such Investor;

               (e)  in the event the Company selects an underwriter for the
offering, the Company shall enter into and perform its reasonable obligations
under an underwriting agreement, in usual and customary form, including, without
limitation, customary indemnification and contribution obligations, with the
underwriter of such offering;

               (f)  if required by the underwriter, at the request of the
Investor, the Company shall furnish, on the date that Registrable Securities or
Additional Registrable Securities, as applicable, are delivered to an
underwriter, if any, for sale in connection with the Registration Statement (i)
an opinion, dated as of such date, from counsel representing the Company for
purposes of such Registration Statement, in form, scope and substance as is
customarily given in an underwritten public offering, addressed to the
underwriter and the Investor and (ii) a letter, dated such date, from the
Company's independent certified public accountants in form and substance as is
customarily given by independent certified public accountants to underwriters in
an underwritten public offering, addressed to the underwriter and the Investor;

               (g)  make reasonable effort to prevent the issuance of any stop
order or other suspension of effectiveness and, if such order is issued, obtain
the withdrawal of any such order at the earliest possible moment;

                                       5
<PAGE>

               (h)  furnish to the Investor at least five copies of the
Registration Statement and any post-effective amendment thereto, including
financial statements and schedules by courier pursuant to the notice
requirements of Section 10.4 of the Purchase Agreement;

               (i)  prior to any public offering of Registrable Securities or
Additional Registrable Securities, use its reasonable best efforts to register
or qualify or cooperate with the Investor and its counsel in connection with the
registration or qualification of such Registrable Securities or Additional
Registrable Securities, as applicable, for offer and sale under the securities
or blue sky laws of such jurisdictions as the Investor reasonably requests in
writing and do any and all other reasonable acts or things necessary or
advisable to enable the distribution in such jurisdictions of the Registrable
Securities or Additional Registrable Securities covered by the Registration
Statement;

               (j)  cause all Registrable Securities or Additional Registrable
Securities covered by a Registration Statement to be listed on each securities
exchange, interdealer quotation system or other market on which similar
securities issued by the Company are then listed;

               (k)  immediately notify the Investor, at any time when a
Prospectus relating to the Registrable Securities or Additional Registrable
Securities is required to be delivered under the Securities Act, upon discovery
that, or upon the happening of any event as a result of which, the Prospectus
included in such Registration Statement, as then in effect, includes an untrue
statement of a material fact or omits to state any material fact required to be
stated therein or necessary to make the statements therein not misleading in the
light of the circumstances then existing, and at the request of any such holder,
promptly prepare and furnish to such holder a reasonable number of copies of a
supplement to or an amendment of such Prospectus as may be necessary so that, as
thereafter delivered to the purchasers of such Registrable Securities or
Additional Registrable Securities, as applicable, such Prospectus shall not
include an untrue statement of a material fact or omit to state a material fact
required to be stated therein or necessary to make the statements therein not
misleading in the light of the circumstances then existing; and

               (l)  otherwise use its best efforts to comply with all applicable
rules and regulations of the SEC under the 1933 Act and the 1934 Act, take such
other actions as may be reasonably necessary to facilitate the registration of
the Registrable Securities and Additional Registrable Securities, if applicable,
hereunder.

                                       6
<PAGE>

          4.   Obligations of the Investor.
               ---------------------------

               (a)  It shall be a condition precedent to the obligations of the
Company to complete the registration pursuant to this Agreement with respect to
the Registrable Securities or Additional Registrable Securities, as applicable,
that the Investor shall furnish in writing to the Company such information
regarding itself, the Registrable Securities or Additional Registrable
Securities, as applicable, held by it and the intended method of disposition of
the Registrable Securities or Additional Registrable Securities, as applicable,
held by it, as shall be reasonably required to effect the registration of such
Registrable Securities or Additional Registrable Securities, as applicable, and
shall execute such documents in connection with such registration as the Company
may reasonably request. At least fifteen (15) business days prior to the first
anticipated filing date of any Registration Statement, the Company shall notify
the Investor of the information the Company requires from the Investor if the
Investor elects to have any of the Registrable Securities or Additional
Registrable Securities included in the Registration Statement. The Investor
shall provide such information to the Company at least ten (10) business days
prior to the first anticipated filing date of such Registration Statement if the
Investor elects to have any of the Registrable Securities or Additional
Registrable Securities included in the Registration Statement.

               (b)  The Investor, by its acceptance of the Registrable
Securities and Additional Registrable Securities, if any, agrees to cooperate
with the Company as reasonably requested by the Company in connection with the
preparation and filing of a Registration Statement hereunder.

               (c)  In the event the Company determines to engage the services
of an underwriter, the Investor agrees to enter into and perform its obligations
under an underwriting agreement, in usual and customary form, including, without
limitation, customary indemnification and contribution obligations, with the
managing underwriter of such offering and take such other actions as are
reasonably required in order to expedite or facilitate the dispositions of the
Registrable Securities or Additional Registrable Securities, as applicable.

               (d)  The Investor agrees that, upon receipt of any notice from
the Company of the happening of any event rendering a Registration Statement no
longer effective, the Investor will immediately discontinue disposition of
Registrable Securities or Additional Registrable Securities pursuant to the
Registration Statement covering such Registrable Securities or Additional
Registrable Securities, until the Investor's receipt of the copies of the
supplemented or amended prospectus filed with the SEC and declared effective
and, if so directed by the Company, the Investor shall deliver to the Company
(at the expense of the Company) or destroy (and deliver to the Company a
certificate of destruction) all copies in the Investor's possession of the
prospectus covering the Registrable Securities or Additional Registrable
Securities, as applicable, current at the time of receipt of such notice.

                                       7
<PAGE>

               (e)  The Investor may not participate in any underwritten
registration hereunder unless it (i) agrees to sell the Registrable Securities
or Additional Registrable Securities, as applicable, on the basis provided in
any underwriting arrangements in usual and customary form entered into by the
Company, (ii) completes and executes all questionnaires, powers of attorney,
indemnities, underwriting agreements and other documents reasonably required
under the terms of such underwriting arrangements, and (iii) agrees to pay its
pro rata share of all underwriting discounts and commissions and any expenses in
excess of those payable by the Company pursuant to the terms of this Agreement.

          5.   Indemnification.
               ---------------

               (a)  Indemnification by Company.  The Company agrees to indemnify
                    --------------------------
and hold harmless, to the fullest extent permitted by law the Investor, its
officers, directors, partners and employees and each person who controls such
Investor (within the meaning of the 1933 Act) against all losses, claims,
damages, liabilities, costs (including, without limitation, reasonable
attorney's fees) and expenses imposed on such person caused by (i) any untrue or
alleged untrue statement of a material fact contained in any Registration
Statement, Prospectus or any preliminary prospectus or any amendment or
supplement thereto or any omission or alleged omission to state therein a
material fact required to be stated therein or necessary to make the statements
therein not misleading, except insofar as the same are based upon any
information furnished in writing to the Company by such Investor, expressly for
use therein, or (ii) any violation by the Company of any federal, state or
common law, rule or regulation applicable to the Company in connection with any
Registration Statement, Prospectus or any preliminary prospectus, or any
amendment or supplement thereto, and shall reimburse in accordance with
subparagraph (c) below, each of the foregoing persons for any legal and any
other expenses reasonably incurred in connection with investigating or defending
any such claims. The foregoing is subject to the condition that, insofar as the
foregoing indemnities relate to any untrue statement, alleged untrue statement,
omission or alleged omission made in any preliminary prospectus or Prospectus
that is eliminated or remedied in any Prospectus or amendment or supplement
thereto, the above indemnity obligations of the Company shall not inure to the
benefit of any indemnified party if a copy of such corrected Prospectus or
amendment or supplement thereto had been made available to such indemnified
party and was not sent or given by such indemnified party at or prior to the
time such action was required of such indemnified party by the 1933 Act and if
delivery of such Prospectus or amendment or supplement thereto would have
eliminated (or been a sufficient defense to) any liability of such indemnified
party with respect to such statement or omission. Indemnity under this Section
5(a) shall remain in full force and effect regardless of any investigation made
by or on behalf of any indemnified party and shall survive the permitted
transfer of the Registrable Securities and Additional Registrable Securities.

               (b)  Indemnification by Investor.  In connection with any
                    ---------------------------
registration the terms of this Agreement, the Investor will furnish to the
Company in writing such information as the Company reasonably requests
concerning the holders of Registrable Securities and Additional Registrable
Securities or the proposed manner of distribution for use in connection with any
Registration Statement or Prospectus and agrees to indemnify and hold harmless,
to the fullest extent permitted by law, the Company, its directors, officers,
employees,

                                       8
<PAGE>

stockholders and each person who controls the Company (within the meaning of the
1933 Act) against any losses, claims, damages, liabilities and expense
(including reasonable attorney's fees) resulting from any untrue statement of a
material fact or any omission of a material fact required to be stated in the
Registration Statement or Prospectus or preliminary prospectus or amendment or
supplement thereto or necessary to make the statements therein not misleading,
to the extent, but only to the extent that such untrue statement or omission is
contained in any information furnished in writing by such Investor to the
Company specifically for inclusion in such Registration Statement or Prospectus
or amendment or supplement thereto and that such information was substantially
relied upon by the Company in preparation of the Registration Statement or
Prospectus or any amendment or supplement thereto. In no event shall the
liability of an Investor be greater in amount than the dollar amount of the
proceeds (net of all expense paid by such Investor and the amount of any damages
such holder has otherwise been required to pay by reason of such untrue
statement or omission) received by such Investor upon the sale of the
Registrable Securities or Additional Registrable Securities included in the
Registration Statement giving rise to such indemnification obligation.

               (c)  Conduct of Indemnification Proceedings. Any person entitled
                    --------------------------------------
to indemnification hereunder shall (i) give prompt notice to the indemnifying
party of any claim with respect to which it seeks indemnification and (ii)
permit such indemnifying party to assume the defense of such claim with counsel
reasonably satisfactory to the indemnified party; provided that any person
                                                  --------
entitled to indemnification hereunder shall have the right to employ separate
counsel and to participate in the defense of such claim, but the fees and
expenses of such counsel shall be at the expense of such person unless (a) the
indemnifying party has agreed to pay such fees or expenses, or (b) the
indemnifying party shall have failed to assume the defense of such claim and
employ counsel reasonably satisfactory to such person or (c) in the reasonable
judgment of any such person, based upon written advice of its counsel, a
conflict of interest exists between such person and the indemnifying party with
respect to such claims (in which case, if the person notifies the indemnifying
party in writing that such person 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 such claim on behalf of such person); and
provided, further, that the failure of any indemnified party to give notice as
--------  -------
provided herein shall not relieve the indemnifying party of its obligations
hereunder, except to the extent that such failure to give notice shall
materially adversely affect the indemnifying party in the defense of any such
claim or litigation. It is understood that the indemnifying party shall not, in
connection with any proceeding in the same jurisdiction, be liable for fees or
expenses of more than one separate firm of attorneys at any time for all such
indemnified parties. No indemnifying party will, except with the consent of the
indemnified party, consent to entry of any judgment or enter into any settlement
that does not include as an unconditional term thereof the giving by the
claimant or plaintiff to such indemnified party of a release from all liability
in respect of such claim or litigation.

               (d)  Contribution.  If for any reason the indemnification
                    ------------
provided for in the preceding paragraphs (a) and (b) is unavailable to an
indemnified party or insufficient to hold it harmless, other than as expressly
specified therein, then the indemnifying party shall contribute to the amount
paid or payable by the indemnified party as a result of such loss, claim, damage
or liability in such proportion as is appropriate to reflect the relative fault
of the indemnified party

                                       9
<PAGE>

and the indemnifying party, as well as any other relevant equitable
considerations. No person guilty of fraudulent misrepresentation within the
meaning of Section 11(f) of the 1933 Act shall be entitled to contribution from
any person not guilty of such fraudulent misrepresentation. In no event shall
the contribution obligation of a holder of Registrable Securities or Additional
Registrable Securities be greater in amount than the dollar amount of the
proceeds (net of all expenses paid by such holder and the amount of any damages
such holder has otherwise been required to pay by reason of such untrue or
alleged untrue statement or omission or alleged omission) received by it upon
the sale of the Registrable Securities or Additional Registrable Securities
giving rise to such contribution obligation.

          6.   Miscellaneous.
               -------------

               (a)  Amendments and Waivers.  This Agreement may be amended only
                    ----------------------
by a writing signed by the parties hereto. The Company may take any action
herein prohibited, or omit to perform any act herein required to be performed by
it, only if the Company shall have obtained the written consent to such
amendment, action or omission to act, of the Investor.

               (b)  Notices.  All notices and other communications provided for
                    -------
or permitted hereunder shall be made as set forth in Section 10.4 of the
Purchase Agreement.

               (c)  Assignments and Transfers by Investor.  This Agreement and
                    -------------------------------------
all the rights and obligations of the Investor hereunder may not be assigned or
transferred to any transferee or assignee except to an affiliate of the Investor
who is a subsequent holder of any Warrants, Registrable Securities or Additional
Registrable Securities.

               (d)  Assignments and Transfers by the Company.  This Agreement
                    ----------------------------------------
may not be assigned by the Company without the prior written consent of
Investor, except that without the prior written consent of the Investor, but
after notice duly given, the Company shall assign its rights and delegate its
duties hereunder to any successor-in-interest corporation, and such successor
-in-interest shall assume such rights and duties, in the event of a merger or
consolidation of the Company with or into another corporation or the sale of all
or substantially all of the Company's assets.

               (e)  Benefits of the Agreement.  The terms and conditions of this
                    -------------------------
Agreement shall inure to the benefit of and be binding upon the respective
permitted successors and assigns of the parties. Nothing in this Agreement,
express or implied, is intended to confer upon any party other than the parties
hereto or their respective successors and assigns any rights, remedies,
obligations, or liabilities under or by reason of this Agreement, except as
expressly provided in this Agreement.

               (f)  Counterparts.  This Agreement may be executed in two or more
                    ------------
counterparts, each of which shall be deemed an original, but all of which
together shall constitute one and the same instrument.

                                      10
<PAGE>

               (g)  Titles and Subtitles.  The titles and subtitles used in this
                    --------------------
Agreement are used for convenience only and are not to be considered in
construing or interpreting this Agreement.

               (h)  Severability.  If one or more provisions of this Agreement
                    ------------
are held to be unenforceable under applicable law, such provision shall be
excluded from this Agreement and the balance of this Agreement shall be
interpreted as if such provision were so excluded and shall be enforceable in
accordance with its terms to the fullest extent permitted by law.

               (i)  Further Assurances.  The parties shall execute and deliver
                    ------------------
all such further instruments and documents and take all such other actions as
may reasonably be required to carry out the transactions contemplated hereby and
to evidence the fulfillment of the agreements herein contained.

               (j)  Entire Agreement.  This Agreement is intended by the parties
                    ----------------
as a final expression of their agreement and intended to be a complete and
exclusive statement of the agreement and understanding of the parties hereto in
respect of the subject matter contained herein. This Agreement supersedes all
prior agreements and understandings between the parties with respect to such
subject matter.

               (k)  Applicable Law.  This Agreement shall be governed by, and
                    --------------
construed in accordance with, the laws of the Commonwealth of Massachusetts
without regard to principles of conflicts of law.

                                      11
<PAGE>

          IN WITNESS WHEREOF, the parties have executed this Agreement as of the
date indicated above.

The Company:                  Boston Life Sciences, Inc.

                              By: /s/ Marc Lanser
                                 -------------------------
                              Name: Marc Lanser, MD
                              Title: Executive VP & Chief Scientific Officer

The Investor:                 Pictet Global Sector Fund-Biotech

                              By: /s/ Jean Pilloud
                                 -------------------------
                              Name: Mr. Jean Pilloud
                              Title: Director

                              By: /s/ Yves Martignier
                                 -------------------------
                              Name: Mr. Yves Martignier
                              Title: Director

                                      12

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