EXHIBIT 15.1


July 27, 2001


The Board of Directors and Stockholders of Genentech, Inc.

We are aware of the incorporation by reference in the Registration Statements
pertaining to the Genentech, Inc. Tax Reduction Investment Plan, the 1999
Stock Plan, the 1996 Stock Option/Stock Incentive Plan, the 1994 Stock Option
Plan, the 1990 Stock Option/Stock Incentive Plan, and the 1991 Employee Stock
Plan and in the related prospectuses, as applicable, contained in such
Registration Statements of our report dated July 9, 2001 relating to the
unaudited condensed consolidated interim financial statements of Genentech,
Inc. which are included in its Form 10-Q for the quarter ended June 30, 2001.

Pursuant to Rule 436(c) of the Securities Act of 1933 our report is not a part
of the registration statement prepared or certified by accountants within the
meaning of section 7 or 11 of the Securities Act of 1933.


                                                         Very truly yours,




                                                         /s/ERNST & YOUNG LLP
                                                         --------------------
                                                            Ernst & Young LLP