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                                 EXHIBIT 5-A(1)
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[LETTERHEAD OF GENENTECH, INC.]
 
                                                                October 25, 1995
 
Genentech, Inc.
460 Point San Bruno Boulevard
South San Francisco, California 94080
 
Ladies and Gentlemen:
 
     I am General Counsel of Genentech, Inc. (the "Company") and am rendering
this opinion in connection with the filing by the Company of a Post-Effective
Amendment on Form S-8 (the "Amendment") to a Registration Statement on Form S-4
(No. 33-59949) (the "Registration Statement") with the Securities and Exchange
Commission covering the offering of up to 1,573,360 shares of the Company's
Callable Putable Common Stock, $.02 par value ("Special Common Stock"), and the
1,573,360 shares of Common Stock, par value $0.02 per share, into which such
shares of Special Common Stock are subject to conversion in accordance with the
provisions of the Company's Certificate of Incorporation (together with the
shares of Special Common Stock, the "Shares"), pursuant to the Company's 1991
Employee Stock Plan, as amended (the "Plan").
 
     In connection with this opinion, I have examined the Amendment, and related
Prospectuses, the Registration Statement, the Company's Certificate of
Incorporation and By-laws, as amended, and such other documents, records,
certificates, memoranda and other instruments as in my judgment are necessary as
a basis for this opinion.
 
     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 Plan, the
Registration Statement and related Prospectus, will be validly issued, fully
paid, and nonassessable.
 
     I consent to the filing of this opinion as an exhibit to the Amendment.
 
                                          Very truly yours,
 
                                          By: /s/  STEPHEN G. JUELSGAARD
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                                                   Stephen G. Juelsgaard
                                                     Vice President and
                                                      General Counsel