EXHIBIT 5.1

               [HELLER EHRMAN WHITE & MCAULIFFE LLP LETTERHEAD]



November 1, 2000

ALZA Corporation
1900 Charleston Road
Mountain View, CA 94039-7210

     RE: Registration Statement on Form S-3

Ladies and Gentlemen:

     We have acted as counsel to ALZA Corporation, a Delaware corporation (the
"Company"), in connection with the Registration Statement on Form S-3 to be
filed with the Securities and Exchange Commission on or about September 22, 2000
(as may be further amended or supplemented, the "Registration Statement") for
the purpose of registering under the Securities Act of 1933, $1,090,000
aggregate principal amount at maturity of the Company's Zero Coupon Convertible
Subordinated Debentures due July 28, 2020 (the "Debentures") and the shares of
the Company's common stock, par value $.005 per share, issuable upon conversion
of the Debentures (the "Conversion Shares") to be sold by certain selling
securityholders listed in the Registration Statement (the "Selling
Securityholders"). The Debentures were issued pursuant to an Indenture, dated as
of July 28, 2000, between the Company and The Chase Manhattan Bank and Trust
Company, National Association, as trustee (the "Indenture").

     We have assumed the authenticity of all records, documents and instruments
submitted to us as originals, the genuineness of all signatures, the legal
capacity of natural persons and the conformity to the originals of all records,
documents and instruments submitted to us as copies.

     In rendering our opinion, we have examined the following records,
documents, instruments and certificates and such additional certificates
relating to factual matters as we have deemed necessary or appropriate for an
opinion:

     (a)  The Restated Certificate of Incorporation of the Company, certified by
the Secretary of State of the State of Delaware;

     (b)  The Bylaws of the Company, certified to us by an officer of the
Company as being complete and in full force and effect as of the date of this
opinion;

     (c)  A Certificate of an officer of the Company (i) attaching records
certified to us as constituting all records of proceedings and actions of the
Board of Directors, including any committee thereof, and stockholders of the
Company relating to the Debentures, the Indenture, the


Conversion Shares and the Registration Statement, and (ii) certifying as to
certain factual matters;

     (d)  The Registration Statement and the Pre-Effective Amendment No. 1
thereto;

     (e)  The Indenture, including the Form of Debenture attached thereto; and

     (f)  Representations from the Company's transfer agent as to the number of
shares of the Company's common stock that were outstanding on October 15, 2000.

     We have assumed that the number of shares of common stock outstanding has
not changed from October 15, 2000 to the date of this letter and that the number
of Conversion Shares will be less than 763,601,858 the number of shares of
common stock of the Company currently authorized but not outstanding or
otherwise reserved for issuance, and that this number of shares of common stock
of the Company will be available for issuance at the time the Debentures are
converted.

     This opinion is limited to the federal laws of the United States of
America, the General Corporation Law of the State of Delaware (which includes
applicable provisions of the Delaware Constitution and reported judicial
decisions interpreting the Delaware General Corporation Law and the Delaware
Constitution) and, insofar as it relates to the enforceability opinion
expressed in paragraph 1, the laws of the State of New York, and we disclaim any
opinion as to the laws of any other jurisdiction. We express no opinion as to
the applicable choice of law rules that may affect the interpretation or
enforcement of the Indenture and the Debentures; the enforceability of any
waiver of immunities contained in the Indenture or the Debentures; or the
enforceability of any liquidated damages provision contained in the Indenture or
the Debentures. We further disclaim any opinion as to any other statute, rule,
regulation, ordinance, order or other promulgation of any other jurisdiction or
any regional or local governmental body.

     Based upon the foregoing and our examination of such questions of law as we
have deemed necessary or appropriate for the purpose of this opinion, and
assuming that (i) the Registration Statement becomes and remains effective
during the period when the Debentures and Conversion Shares are offered and
sold, (ii) the Conversion Shares will be issued, delivered and paid for in
accordance with the terms of the Debentures and (iii) appropriate certificates
evidencing the Conversion Shares will be executed and delivered by the Company,
it is our opinion that:

     1.   The Debentures, when sold by the Selling Securityholders in the manner
described in the Registration Statement, will constitute the legal, valid and
binding obligations of the Company, enforceable against it in accordance with
their terms, subject to applicable bankruptcy, insolvency, fraudulent
conveyance, reorganization, moratorium and similar laws affecting creditors'
rights and remedies generally, and subject, as to enforceability, to general
principles of equity, including principles of commercial reasonableness, good
faith and fair dealing (regardless of whether enforcement is sought in a
proceeding at law or in equity).

     2.   When issued upon conversion of the Debentures and upon receipt by the
Company of the conversion price therefor, the Conversion Shares will be legally
issued, fully paid and non-assessable.

     This opinion is rendered to you in connection with the Registration
Statement. This opinion may not be relied upon by you for any other purpose
without our prior written consent.

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We disclaim any obligation to advise you of any change of law that occurs, or
any facts of which we may become aware, after the date of this opinion.

     We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement and to the reference to us under the caption "Legal
Matters" in the Registration Statement.

                                  Very truly yours,



                                  /S/ HELLER EHRMAN WHITE & MCAULIFFE LLP

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