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                                                                     Exhibit 4.1
                     [3-DIMENSIONAL PHARMACEUTICALS LOGO]

                      3-DIMENSIONAL PHARMACEUTICALS, INC.
             INCORPORATED UNDER THE LAWS OF THE STATE OF DELAWARE

     COMMON STOCK                                            CUSIP _________
                                                                 SEE REVERSE FOR
                                                             CERTAIN DEFINITIONS

THIS
CERTIFIES
THAT


is the owner of

           FULLY PAID AND NON-ASSESSABLE SHARES OF THE COMMON STOCK
                              PAR VALUE $0.001 OF

                      3-DIMENSIONAL PHARMACEUTICALS, INC.

(hereinafter called the "Corporation"), transferable on the books of the
Corporation by the holder hereof in person or by duly authorized attorney, upon
surrender of this Certificate properly endorsed. This Certificate and the shares
represented hereby are issued and shall be held subject to all the provisions of
the Certificate of Incorporation, as amended, and the Bylaws of the Corporation,
as amended (copies of which are on file at the office of the Transfer Agent), to
all of which the holder of this Certificate by acceptance hereof assents.

     This Certificate is not valid unless countersigned and registered by the
Transfer Agent and Registrar.

     Witness the facsimile seal of the Corporation and the facsimile signatures
of its duly authorized officers.

Date:


Secretary                                          Chief Executive Officer
                  [3-DIMENSIONAL
                  PHARMACEUTICALS SEAL]

                                                   COUNTERSIGNED AND REGISTERED:
                                         AMERICAN STOCK TRANSFER & TRUST COMPANY
                                                   (New York, NY) TRANSFER AGENT
                                                                   AND REGISTRAR
                                       BY
                                                            AUTHORIZED SIGNATURE
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     A FULL STATEMENT OF THE RELATIVE RIGHTS, INTERESTS, PREFERENCES AND
     RESTRICTIONS OF EACH CLASS OF STOCK WILL BE FURNISHED BY THE CORPORATION TO
     ANY STOCKHOLDER UPON WRITTEN REQUEST, WITHOUT CHARGE.

     The following abbreviations, when used in the inscription on the face of
this certificate, shall be construed as though they were written out in full
according to applicable laws or regulations:

     TEN COM -- as tenants in common UNIF GIFT MIN ACT -- ______Custodian_______
     TEN ENT -- as tenants by the entireties              (Cust)         (Minor)
     JT TEN  -- as joint tenants with right of     under Uniform Gifts to Minors
                survivorship and not as tenants      Act_______________________
                in common                                       (State)

    Additional abbreviations may also be used though not in the above list.

     FOR VALUE RECEIVED, _____________hereby sell, assign and transfer unto

PLEASE INSERT SOCIAL SECURITY OR OTHER
  IDENTIFYING NUMBER OF ASSIGNEE

-------------------------------------

--------------------------------------------------------------------------------
PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS, INCLUDING ZIP CODE OF ASSIGNEE

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_________________________________________________________________________Shares

of the capital stock represented by the within Certificate, and do hereby
irrevocably constitute and appoint
________________________________________________________________________Attorney

to transfer the said stock on the books of the within named Corporation with
full power of substitution in the premises.

Dated________________________


                                  ----------------------------------------------
                                NOTICE: THE SIGNATURE(S) TO THIS ASSIGNMENT MUST
                                     CORRESPOND WITH THE NAME(S) AS WRITTEN UPON
                                THE FACE OF THE CERTIFICATE IN EVERY PARTICULAR,
                                               WITHOUT ALTERATION OR ENLARGEMENT
                                                         OR ANY CHANGE WHATEVER.


                   Signature(s) Guaranteed______________________________________

                    THE SIGNATURE(S) MUST BE GUARANTEED BY AN ELIGIBLE GUARANTOR
                 INSTITUTION (BANKS, STOCKBROKERS, SAVINGS AND LOAN ASSOCIATIONS
                      AND CREDIT UNIONS WITH MEMBERSHIP IN AN APPROVED SIGNATURE
                 GUARANTEE MEDALLION PROGRAM, PURSUANT TO S.E.C. RULE 12 AD. 13.
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KEEP THIS CERTIFICATE IN A SAFE PLACE. IF IT IS LOST, STOLEN, MUTILATED OR
DESTROYED, THE CORPORATION WILL REQUIRE A BOND OF INDEMNITY AS A CONDITION TO
THE ISSUANCE OF A REPLACEMENT CERTIFICATE.