EXHIBIT 5

Genentech, Inc.
1 DNA Way
South San Francisco, California 94080

April 26, 2002

Ladies and Gentlemen:

I am Senior Vice President, General Counsel and Secretary of Genentech, Inc.
(the "Company"). In connection with this opinion, I have examined the following
documents:

   -  the Company's Registration Statement on Form S-8 (the "Registration
      Statement") to be filed with the Securities and Exchange Commission
      covering the offering of 15,000,000 shares of the Company's Common Stock,
      par value $.02 per share (the "Shares"), pursuant to the Company's 1999
      Stock Plan, as amended and restated on December 8, 2000 (the "Plan") and
      the related Prospectus;

   -  the Company's Amended and Restated Certificate of Incorporation and
      Bylaws; and

   -  such other documents, records, certificates, memoranda and other
      instruments as I deem necessary as a basis for this opinion.

I have assumed the genuineness and authenticity of all documents submitted to me
as originals, the conformity to originals of all documents submitted to me as
copies thereof, and the due execution and delivery of all documents where due
execution and delivery are a prerequisite to the effectiveness thereof.

On the basis of the foregoing, and in reliance thereon, I am of the opinion that
the Shares, when sold and issued in accordance with the Registration Statement
and the Plan and the related Prospectus, will be validly issued, fully paid, and
nonassessable.

I am admitted to practice only in the State of California. The opinions set
forth herein are limited to matters of the General Corporation Law of Delaware
and the federal securities laws of the United States.

I consent to the filing of this opinion as an exhibit to the Registration
Statement.

                                          Very truly yours,

                                          /s/ STEPHEN G. JUELSGAARD

                                          Stephen G. Juelsgaard
                                          Senior Vice President, General Counsel
                                          and Secretary