EXHIBIT 23.1

           CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

     We consent to the reference to our firm under the caption "Experts" in the
Post-Effective Amendment No. 2 to the Registration Statement (Form S-3, No.
333-121732) and related Prospectus of Cell Genesys, Inc. for the registration of
its convertible senior notes and underlying shares of its common stock and to
the incorporation by reference therein of our reports dated February 24, 2005,
with respect to the consolidated financial statements of Cell Genesys, Inc.,
Cell Genesys, Inc.'s management's assessment of the effectiveness of internal
control over financial reporting, and the effectiveness of internal control over
financial reporting of Cell Genesys, Inc., included in its Annual Report (Form
10-K) for the year ended December 31, 2004, filed with the Securities and
Exchange Commission.

                                             /s/ Ernst & Young LLP

Palo Alto, California
March 11, 2005