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                                                                      Exhibit 4d
                                   AGREEMENT

     THIS AGREEMENT, dated March 19, 1998 (this "AGREEMENT"), by and between 
DynaGen, Inc. a Delaware corporation ("DYNAGEN"), and The Endeavour Capital
Fund, S.A., a British Virgin Islands corporation ("ENDEAVOUR").

                                WITNESSETH THAT:

     WHEREAS, DynaGen and Endeavour are parties to that certain Stock Purchase
Agreement,dated as of August 20, 1997 (the "STOCK PURCHASE AGREEMENT");
providing, among other things, for the sale and purchase of the Series D
Convertible Preferred Stock, $.01 par value per share (the "SERIES D PREFERRED
STOCK"), of DynaGen; and 

     WHEREAS, DynaGen wishes to sell and Endeavour wishes to purchase a tranche
of the Series D Preferred Stock; 

     NOW, THEREFORE, in consideration of this Agreement and intending to be
legally bound hereby, the parties hereto agree as follows; 

     1. SALE AND PURCHASE. DynaGen shall sell, and Endeavour shall purchase,
the first tranche of the Series D Preferred Stock in the principal amount of
$500,000 (the "FIRST TRANCHE") required to be purchased and sold in accordance
with the Stock Purchase Agreement and this Agreement.

     2. DELIVERY OF SHARES AND PAYMENT. Endeavour shall pay the  purchase price
for the First Tranche by delivering immediately available good funds in United
States Dollars to Samuel Krieger, Esq. (the "ESCROW AGENT") who shall promptly
notify DynaGen of the receipt of such funds. Such funds shall be delivered to
the Escrow Agent promptly, but in any event within two business days after the
date hereof. Promptly following such notice, but in any event within two
business days thereafter, DynaGen shall deliver a certificate (the
"CERTIFICATE") for the shares of Series D Preferred Stock constituting the
First Tranche duly executed on behalf of DynaGen to the Escrow Agent. Promptly,
but in any event within one business day of receipt of the Certificate, the
Escrow Agent shall deliver payment for the First Tranche to DynaGen by wire
transfer of immediately available good funds in United States. Time is of the
essence with respect to the provisions of this SECTION 2.

     3. SETTLEMENT OF PENALTIES. Concurrently with the delivery of the
Certificate, DynaGen shall execute and deliver to the Escrow Agent a debenture
in the original principal amount of $328,500 and otherwise in the form of
EXHIBIT A hereto (the "DEBENTURE"). The Debenture is being delivered to
Endeavour in consideration of the waiver of (a) all amounts owed by DynaGen
under Section 2. (b)(i) of the Registration Rights Agreement, dated as of
August 20, 1997, by and between DynaGen and Endeavour (the "REGISTRATION RIGHTS
AGREEMENT") and (b) all amounts incurred by DynaGen up to the date hereof under
Section 2. (b)(ii) of the Registration Rights Agreement, which for the purposes
hereof is agreed to be $93,750 (the "REGISTRATION PENALTY").  Upon the delivery
of the Certificate, the first Computation Date," as defined in said Section
2(b), shall be extended to a date    
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sixty days from the date hereof, provided, that DynaGen shall pay to Endeavour
$18,750 per month (prorated for periods of less than one month) from the date
hereof until the earlier of (i) the first Computation Date, as extended hereby,
or (ii) the date that a registration statement contemplated by the Registration
Rights Agreement is declared effective by the Securities and Exchange
Commission. If such registration statement has not been declared effective on
such first Computation Date as extended hereby, then DynaGen shall make an
additional payment of $7,500 per week to Endeavour (in addition to the monthly
payment set forth above) until the earlier of (X) the time the aggregate amount
of such additional payment equals the Registration Penalty or (Y) such
registration statement is declared effective by the Securities and Exchange
Commission.

     4. Waivers and Acknowledgments. Endeavour hereby waives the conditions set
forth below to its obligation to purchase the First Tranche. This waiver is
solely for the purposes of the sale of the First Tranche and is not a
continuing waiver nor is it an agreement to waive the same requirements in the
future. Endeavour hereby waives the requirements of the Stock Purchase
Agreement set forth in Section 4i.(a) (requiring a five day prior written
notice), 4i.(b) (limiting each tranche to $400,000), and 4i.(c)(i), (iii) and
(iv) (requiring effectiveness of the Registration Statement and certain other
matters). Endeavour acknowledges that it has been informed that DynaGen has
received a notice, dated February 26, 1998, from the NASDAQ stating that
DynaGen does not meet the listing requirements of the NASDAQ and is subject to
delisting.

     5. Representations and Warranties. Except as set forth on Exhibit A 
hereto, the representations and warranties of DynaGen set forth in Section 3 of
the Stock Purchase Agreement are true and correct in all material respects.

     6. Recent Transactions. Exhibit B hereto sets forth a true, correct and
complete list of all material transactions entered into by DynaGen since August
20, 1997.

     7. Costs and Expenses. DynaGen will pay up $13,000.00 of the legal fees of
Endeavour incurred since August 20, 1997.

     8. Miscellaneous. Section 10 of the Stock Purchase Agreement shall also
govern this Agreement.


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

                                        DYNAGEN, INC.

                                        By: /s/ Dhananjay Wadekar
                                           ----------------------------
                                        Name: Dhananjay Wadekar
                                        Title: Chairman of the Board


                                        THE ENDEAVOUR CAPITAL FUND S.A.

                                        By:
                                           ----------------------------
                                        Name: Shmulie Margulies
                                        Title: Director

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


                                          DYNAGEN, INC.


                                          By: 
                                              ------------------------------
                                          Name: Dhananjay Wadekar
                                          Title: Chairman of the Board



                                          THE ENDEAVOUR CAPITAL FUND S.A.


                                          By: /s/ Shmulie Margulies
                                              ------------------------------
                                          Name: Shmulie Margulies
                                          Title: Director