<PAGE>

        COMMON STOCK                                       COMMON STOCK

           NUMBER               [SUPERGEN LOGO]               SHARES

         SUPG  0908

INCORPORATED UNDER THE LAWS OF                       SEE REVERSE FOR STATEMENTS
   THE STATE OF CALIFORNIA                               RELATING TO RIGHTS,
                                                       PREFERENCES, PRIVILEGES 
                                                      AND RESTRICTIONS, IF ANY

                                                              CUSIP 868059 10 6

-------------------------------------------------------------------------------
THIS CERTIFIES THAT




                                  [SPECIMEN]


IS THE HOLDER OF
-------------------------------------------------------------------------------

FULLY PAID AND NONASSESSABLE SHARES OF THE COMMON STOCK, $.001 PAR VALUE, OF

                               SUPERGEN, INC.

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 is not valid until 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.

                          [CERTIFICATE OF STOCK]

                [STATE OF INCORPORATION CHANGED TO DELAWARE]

Dated:

                          [SEAL OF SUPERGEN, INC.]

      /s/ David M. Fineman                   /s/ Dr. Joseph Rubinfeld
          SECRETARY                      PRESIDENT AND CHIEF EXECUTIVE OFFICER


COUNTERSIGNED AND REGISTERED:
   CHASEMELLON SHAREHOLDER SERVICES, L.L.C
                            TRANSFER AGENT
                             AND REGISTRAR

BY:
                      AUTHORIZED SIGNATURE

<PAGE>

     A statement of the rights, preferences, privileges and restrictions 
granted to or imposed upon the respective classes or series of shares and 
upon the holders thereof as established, from time to time, by the Articles 
of Incorporation of the Corporation and by any certificate of determination, 
and the number of shares constituting each class and series and the 
designations thereof, may be obtained by the holder hereof upon written 
request and without charge from the Secretary of the Corporation at its 
corporate headquarters.

     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:

<TABLE>
  <S>                                              <C>
  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                                under Uniform Gifts to Minors
             of survivorship and not as                                 Act..................................
             tenants in common                                                         (State)
                                                   UNIF TRF MIN ACT  -- ..........Custodian (until age......)
                                                                          (Cust)
                                                                        ............ under Uniform Transfers
                                                                          (Minor)
                                                                        to Minors Act........................
                                                                                             (State)
</TABLE>


   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)

______________________________________________________________________________


______________________________________________________________________________


______________________________________________________________________ Shares
of the capital stock represented by the within Certificate, 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 ___________________________


                                          X __________________________________

                                          X __________________________________
                                    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



By _____________________________________________
THE SIGNATURE(S) SHOULD 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 17Ad-15.