EXHIBIT 5.1



                                August 28, 2000


SuperGen, Inc.
Two Annabel Lane, Suite 220
San Ramon, CA  94583

         RE:      REGISTRATION STATEMENT ON FORM S-8

Ladies and Gentlemen:

         We have examined the Registration Statement on Form S-8 to be filed by
you with the Securities and Exchange Commission on or about August 28, 2000 (the
"Registration Statement") in connection with the registration under the
Securities Act of 1933, as amended, of 2,000,000 shares of your Common Stock
reserved for issuance under the 1993 Stock Option Plan (the "Plan"). As your
legal counsel, we have examined the proceedings taken and are familiar with the
proceedings taken and proposed to be taken by you in connection with the sale
and issuance of such Common Stock under the Plan.

         It is our opinion that, when issued and sold in the manner referred to
in the Plan and pursuant to the agreements which accompany the Plan, the Common
Stock issued and sold thereby will be legally and validly issued, fully paid and
non-assessable.

         We consent to the use of this opinion as an exhibit to the Registration
Statement and further consent to the use of our name wherever appearing in the
Registration Statement, including any Prospectus constituting a part thereof,
and any amendments thereto.

                                       Sincerely,

                                       WILSON SONSINI GOODRICH & ROSATI
                                       Professional Corporation

                                       /s/ Wilson Sonsini Goodrich & Rosati