EXHIBIT 23.1

               CONSENT OF ERNST & YOUNG LLP, INDEPENDENT AUDITORS

    We consent to the reference to our firm under the captions "Selected
Financial Data", "Change in Independent Auditors", and "Experts" and to the use
of our report dated October 29, 1999, in Amendment No. 1 to the Registration
Statement (Form S-1, No. 333-89413) and related Prospectus of Maxygen, Inc. for
the registration of 5,750,000 shares of its common stock.

                                        /s/ Ernst & Young LLP

Palo Alto, California

November 19, 1999