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                                                                    Exhibit 10.3

                                PROMISSORY NOTE

$3.0 MILLION                                                      AUGUST 8, 2006

      FOR VALUE RECEIVED, Boston Life Sciences, Inc., a Delaware corporation
("Maker"), hereby unconditionally promises to pay to the order of Robert Gipson
("Lender"), in lawful money of the United States of America and in immediately
available funds, the principal sum of Three Million Dollars ($3,000,000), or, if
less, the aggregate unpaid principal amount of all Advances (defined in Section
1 below) (the "Loan"), together with accrued and unpaid interest thereon, each
due and payable on the dates and in the manner set forth below.

      1. ADVANCES. From time to time prior to the Maturity Date (defined in
Section 2 below), and so long as no Event of Default exists, the Lender shall
make advances (the "Advances") to the Maker, and the Maker may borrow funds from
the Lender hereunder, provided that the aggregate principal amount of all
Advances shall in no event exceed $3,000,000. Each request for an Advance shall
be made by the Maker in writing, delivered to the Lender at least seven (7)
business days prior the requested date of such Advance and shall specify the
date of such Advance, and the amount of such Advance. Each Advance shall be in
the minimum amount of $1,000,000. The Lender shall, and is hereby authorized to,
record on the schedule attached hereto, or to otherwise record in accordance
with its usual practice, the date and amount of each Advance and the date and
amount of each principal payment hereunder, provided, however, that any failure
to so record any Advance or Payment shall not in any manner affect the
obligation of the Maker to repay any Advance in accordance with the terms
hereof.

      2. PRINCIPAL REPAYMENT. The outstanding principal amount of the Loan shall
be due and payable on the earliest to occur of (i) December 31, 2007, (ii) the
date on which the Maker consummates an equity financing in which the aggregate
gross proceeds to the Maker total at least $10,000,000 and (iii) the date on
which the Lender declares an Event of Default (as defined in Section 8 below) to
have occurred (the first of the events set forth in Section 2(i), 2(ii) and
2(iii) to occur being referred to herein as the "Maturity Date"). This Note may
be prepaid in whole or in part at any time without premium or penalty.

      3. INTEREST RATE AND PAYMENTS. Interest shall accrue on each Advance from
the date of such Advance and all unpaid interest shall be due and payable on the
Maturity Date. The Maker promises to pay interest on the outstanding principal
amount of each Advance from the date of such Advance until payment in full of
such Advance at a per annum interest rate equal to (i) nine percent (9%) from
the date hereof to the Maturity Date, (ii) from and after the Maturity Date, or
during the continuance of an Event of Default (as defined below), at the rate
set forth in clause (i) plus two percent (2%), or (iii) if less than the rates
applicable under both clauses (i) and (ii), the maximum rate permissible by law.
Interest shall be calculated on the basis of a 360-day year for the actual
number of days elapsed.

      4. PLACE OF PAYMENT. All amounts payable hereunder shall be payable in
immediately available funds at the office of the Lender, c/o Ingalls & Snyder,
61 Broadway, New York, NY, unless another place of payment shall be specified in
writing by the Lender.

                                                                 Promissory Note
                                                            Dated August 8, 2006
<PAGE>

      5. APPLICATION OF PAYMENTS. Payment on this Note shall be applied first to
costs and expenses due hereunder, if any, then to accrued interest, and
thereafter to the outstanding principal balance hereof. Any principal repayment
or interest payment hereunder not paid when due, whether at stated maturity, by
acceleration or otherwise, shall bear interest at the rate set forth in clause
(ii) of Section 2 hereof (or, if such rate exceeds the maximum rate permitted by
law, then at such maximum rate permitted by law) until paid in full.

      6. REPRESENTATIONS AND WARRANTIES. The Maker represents and warrants to
the Lender that:

            (a) the Maker is duly organized, validly existing, and in good
standing under the laws of its jurisdiction of incorporation and is duly
qualified and in good standing in every other jurisdiction where the nature of
its business or the location or ownership of its properties requires such
qualification and where the failure to be so qualified would reasonably be
expected to have a material adverse effect on the Maker's business, operations,
properties, assets or condition (financial or otherwise);

            (b) the Maker has the full corporate power and authority to execute
and deliver this Note and to perform all of the obligations hereunder, and all
necessary corporate action has been taken to execute and deliver this Note and
to make the borrowings hereunder;

            (c) this Note constitutes the legal, valid, and binding obligations
of the Maker, enforceable against the Maker in accordance with its terms,
subject to applicable bankruptcy, insolvency, reorganization or similar laws
generally affecting the enforcement of the rights of creditors; and

            (d) the execution, delivery and performance by the Maker of this
Note does not (i) violate any provisions of the Maker's Certificate of
Incorporation, as amended, bylaws, as amended, or any contract, agreement, law,
regulation, order, decree or writ to which the Maker or any of its properties
are subject or (ii) require the consent or approval of any person, entity or
authority, including, without limitation, any regulatory authority or
governmental body of the United States of America or any state thereof or any
political subdivision of any of the foregoing.

      7. NEGATIVE COVENANTS. So long as any principal and interest remains
outstanding under this Note, the Maker shall not:

            (a) create, incur, assume, guaranty, become liable with respect to
(contingently or otherwise), or permit to be outstanding any indebtedness for
money borrowed (including, without limitation, any indebtedness evidenced by any
notes, instruments or agreements or in connection with any capitalized lease),
except for the obligations under this Note;

            (b) (i) declare or pay any cash dividend, or make a distribution on,
repurchase, or redeem, any class of stock of the Maker, other than pursuant to
repurchase obligations under existing employee stock purchase or option plans or
(ii) sell, lease, transfer or otherwise dispose of any material assets or
property of the Maker; or

                                                                 Promissory Note
                                                            Dated August 8, 2006

                                       -2-
<PAGE>

            (c) dissolve or liquidate.

      8. DEFAULT. Each of the following events shall be an "Event of Default"
hereunder:

            (a) the Maker fails to pay any of the principal, interest or any
other amounts payable under this Note when and as the same becomes due and
payable;

            (b) the Maker files any petition or action for relief under any
bankruptcy, reorganization, insolvency or moratorium law or any other law for
the relief of, or relating to, Maker, now or hereafter in effect, or seeks the
appointment of a custodian, receiver, trustee (or other similar official) of the
Maker or all or any substantial portion of the Maker's assets, or makes any
assignment for the benefit of creditors or takes any action in furtherance of
any of the foregoing, or fails to generally pay its debts as they become due;

            (c) an involuntary petition is filed, or any proceeding or case is
commenced, against the Maker (unless such proceeding or case is dismissed or
discharged within ninety (90) days of the filing or commencement thereof) under
any bankruptcy, reorganization, arrangement, insolvency, adjustment of debt,
liquidation or moratorium statute now or hereafter in effect, or a custodian,
receiver, trustee, assignee for the benefit of creditors (or other similar
official) is applied for, appointed for the Maker or to take possession, custody
or control of any property of the Maker, or an order for relief is entered
against the Maker in any of the foregoing; or

            (d) any representation or warranty made or deemed made by the Maker
under this Note shall have been false or misleading in any material respect when
made or deemed made.

      9. REMEDIES. Upon the occurrence and during the continuance of an Event of
Default hereunder:

            (a) all unpaid principal, accrued interest and other amounts owing
hereunder shall, at the option of the Lender, and, in the case of an Event of
Default pursuant to Section 8(b) or (c) above, automatically, be immediately
due, payable and collectible by the Lender pursuant to applicable law;

            (b) any and all unpaid principal, interest or other amounts due
under this Note shall thereafter bear interest at the maximum rate set forth in
Section 3 hereof;

            (c) any and all of the Lender's obligations to make any additional
loans or advances hereunder shall automatically terminate and expire; and

            (d) the Lender may exercise any and all rights and remedies it may
have under this Note or under applicable law.

      All rights and remedies shall be cumulative and not exclusive. The failure
of the holder hereof to exercise all or any of its rights, remedies, powers or
privileges hereunder or applicable law, in any instance shall not constitute a
waiver thereof in that or any other instance.

                                                                 Promissory Note
                                                            Dated August 8, 2006

                                       -3-
<PAGE>

      10. EXPENSES. The Maker agrees to and shall pay to the Lender on demand,
any and all expenses, including, without limitation, reasonable attorney's fees
and disbursements, incurred or paid by the Lender in connection herewith,
including, without limitation, such fees, costs and expenses incurred for
collection or enforcement of amounts outstanding hereunder, for protecting,
preserving or enforcing the Lender's rights or remedies (including fees, costs
and expenses relating to any proceedings with respect to the bankruptcy,
reorganization, insolvency, readjustment of debt, dissolution or liquidation of
the Maker).

      11. WAIVER. The Maker, for itself and its legal representatives,
successors and assigns, hereby expressly waives demand, protest, presentment,
notice of dishonor, notice of acceptance, and notice of protest, and all other
demands and notices in connection with the delivery, acceptance, performance,
default or enforcement of this Note and agrees that any extension, renewal or
postponement of the time of payment or any other indulgence to, or release of
any person now or hereafter obligated for the payment of this Note shall not
affect the Maker's liability hereunder.

      12. GOVERNING LAW; CONSENT TO JURISDICTION. THIS NOTE IS INTENDED TO TAKE
EFFECT AS A SEALED INSTRUMENT AND SHALL BE GOVERNED BY, AND CONSTRUED IN
ACCORDANCE WITH, THE LAWS (AND NOT THE LAWS OF CONFLICT) OF THE COMMONWEALTH OF
MASSACHUSETTS. THE MAKER HEREBY IRREVOCABLY SUBMITS TO THE JURISDICTION OF THE
COURTS OF THE COMMONWEALTH OF MASSACHUSETTS AND THE UNITED STATES DISTRICT COURT
FOR THE COMMONWEALTH OF MASSACHUSETTS FOR THE PURPOSE OF ANY SUIT, ACTION OR
OTHER PROCEEDING ARISING OUT OF OR RELATING TO THIS NOTE AND THE MAKER HEREBY
IRREVOCABLY AGREES THAT ALL CLAIMS IN RESPECT OF SUCH ACTION OR PROCEEDING MAY
BE HEARD AND DETERMINED IN ANY SUCH COURT AND IRREVOCABLY WAIVES ANY OBJECTION
IT MAY NOW OR HEREAFTER HAVE AS TO THE VENUE OF ANY SUCH SUIT, ACTION OR
PROCEEDING BROUGHT IN ANY SUCH COURT OR THAT SUCH COURT IS AN INCONVENIENT
FORUM. NOTHING HEREIN SHALL LIMIT THE RIGHT OF THE LENDER TO BRING PROCEEDINGS
AGAINST THE MAKER IN THE COURTS OF ANY OTHER JURISDICTION. ANY JUDICIAL
PROCEEDING BY THE MAKER AGAINST THE LENDER OR ANY AFFILIATE OF THE LENDER
INVOLVING, DIRECTLY OR INDIRECTLY, ANY MATTER IN ANY WAY ARISING OUT OF, RELATED
TO, OR CONNECTED WITH THIS NOTE SHALL BE BROUGHT ONLY IN A COURT IN THE
COMMONWEALTH OF MASSACHUSETTS.

      13. SUCCESSORS AND ASSIGNS. This Note and all obligations of the Maker
hereunder shall be binding upon the successors and assigns of the Maker, and
shall, together with the rights and remedies of the Lender hereunder, inure to
the benefit of the Lender, any future holder of this Note and their respective
successors and assigns, provided, however, the Maker may not transfer or assign
its rights or obligations hereunder without the express written consent of the
Lender, and any purported transfer or assignment by the Maker without the
Lender's written consent shall be null and void. The Lender may assign,
transfer, participate or endorse its rights under this Note without the consent
or approval of the Maker, and all such rights shall inure to the Lender's
successors and assigns. No sales of participations, other sales, assignments,
transfers, endorsements or other dispositions of any rights hereunder or any
portion thereof or interest therein shall in any manner affect the obligations
of the Maker under this Note. Upon request, the Maker shall, at its own expense,
execute and deliver to the assignee of this Note, a

                                                                 Promissory Note
                                                            Dated August 8, 2006

                                       -4-
<PAGE>

replacement Note of equal and like tenor in an amount assigned to and assumed by
such assignee.

      14. WAIVER OF JURY TRIAL AND CERTAIN DAMAGES. THE MAKER AND THE LENDER
EACH WAIVES ITS RIGHT TO A JURY TRIAL WITH RESPECT TO ANY ACTION OR CLAIM
ARISING OUT OF ANY DISPUTE IN CONNECTION WITH THIS NOTE, ANY RIGHTS OR
OBLIGATIONS HEREUNDER OR THE PERFORMANCE OF ANY SUCH RIGHTS OR OBLIGATIONS.
Except as prohibited by law, the Maker waives any right which it may have to
claim or recover in any litigation referred to in the preceding sentence any
special, exemplary, punitive or consequential damages or any damages other than,
or in addition to, actual damages. The Maker (i) certifies that neither the
Lender nor any representative, agent or attorney of the Lender has represented,
expressly or otherwise, that the Lender would not, in the event of litigation,
seek to enforce the foregoing waivers and (ii) acknowledges that, in entering
into the Note, the Lender is relying upon, among other things, the foregoing
waivers and certifications.

      15. ENTIRE AGREEMENT; AMENDMENTS; INVALIDITY. This Note constitutes the
entire agreement and understanding of the parties, and supercedes and replaces
in their entirety any prior discussions, agreements, etc., all of which are
merged herein and therein. None of the terms of this Note may be amended or
otherwise modified except by an instrument executed by each of the Maker and the
Lender. If any term of this Note shall be held to be invalid, illegal or
unenforceable, the validity of all other terms hereof shall in no way be
affected thereby, and this Note shall be construed and be enforceable as if such
invalid, illegal or unenforceable term had not been included herein.

                                                                 Promissory Note
                                                            Dated August 8, 2006

                                      *****

                                      -5-
<PAGE>

      IN WITNESS WHEREOF, this Note has been duly executed as an instrument
under seal as of the date first set forth above.

LENDER:                                        BOSTON LIFE SCIENCES, INC.

                                               By: /s/ Kenneth L. Rice Jr.
                                                   ----------------------------

/s/ Robert L. Gipson                           Printed Name: Kenneth L. Rice Jr.
----------------------
Robert L. Gipson                               Title: EVP & CFO

                                               Address:

                                               85 MAIN STREET
                                               HOPKINTON, MA 01748

ATTEST:

By: /s/ Thomas O. Boucher, Jr.
    --------------------------

Title: NOTARY

             [SEAL]
            10/31/09

<PAGE>

                          ADDENDUM A TO PROMISSORY NOTE

This Addendum to the Promissory Note dated August 8, 2006 between Robert Gipson
("Lender") and Boston Life Sciences, Inc. ("Maker") effective as of August 9,
2006 as follows:

Lender hereby acknowledges (i) that Wilmer Cutler Pickering Hale and Dorr LLP
has served as counsel solely to the Maker in connection with entering into this
note, the Loan and the transactions contemplated hereby, and (ii) that Lender
(a) has sought the advice of his own legal counsel and has not relied upon
Wilmer Cutler Pickering Hale and Dorr LLP, (b) has had an opportunity to fully
discuss and review the terms of this note with Lender's counsel, (c) understands
the contents herein and freely and voluntarily assents to all of the terms and
conditions hereof and the transactions contemplated hereby."

AGREED

                                               BOSTON LIFE SCIENCES, INC.

Lender                                         Maker

/s/ Robert L. Gipson                           By /s/ Kenneth L. Rice Jr.
---------------------                             ------------------------------
Robert L. Gipson
                                               Title EVP & CFO


<PAGE>

                   SCHEDULE OF LOAN AND PAYMENTS OF PRINCIPAL
                               TO PROMISSORY NOTE
                             OF BOSTON LIFE SCIENCES
                              DATED AUGUST 8, 2006

<TABLE>
<CAPTION>
Principal                          Principal
Amount of                          Amount            Unpaid
Advance           Date             Paid              Balance
---------         ----             ---------         -------
<S>               <C>              <C>               <C>
</TABLE>