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                                                                    EXHIBIT 5(a)


                                  June 25, 2001

Anadarko Petroleum Corporation
17001 Northchase Drive
Houston, Texas 77060-2141

         Re:      Registration Statement on Form S-3
                  Zero Yield Puttable Contingent Debt Securities
                  Shares of Common Stock, par value $0.10 per share

Ladies and Gentlemen:

         We have acted as counsel for Anadarko Petroleum Corporation, a Delaware
corporation (the "Company"), in connection with the issuance by it of
$650,000,000 principal amount of its Zero Yield Puttable Contingent Debt
Securities (ZYP-CODES(sm)) due 2021 (the "ZYP-CODES"), pursuant to the First
Supplemental Indenture, dated as of March 13, 2001 (the "First Supplemental
Indenture"), to the Indenture, dated as of March 9, 2001 (the "Base Indenture"
and, together with the First Supplemental Indenture, collectively, the
"Indenture"), between the Company and The Bank of New York, as Trustee (the
"Trustee"), and in connection with the preparation and filing with the
Securities and Exchange Commission (the "SEC") of the Registration Statement (as
defined below). The ZYP-CODES and the up to 6,453,525 shares (the "Shares") of
common stock, par value $0.10 per share, issuable upon conversion of the
ZYP-CODES are being registered for resale by the holders thereof under the
Securities Act of 1933, as amended (the "Act") pursuant to a Registration
Statement on Form S-3 (the "Registration Statement").

         As the basis for the opinions hereinafter expressed, we have examined
(i) the Certificate of Incorporation and Bylaws of the Company, each as amended
to date; (ii) the Registration Statement, as amended to date, including the form
of prospectus included therein and the documents incorporated by reference
therein; (iii) the Indenture; and (iv) such statutes, regulations, corporate
records and documents, certificates of public officials and such other
instruments as we have deemed necessary for the purposes of the opinions
contained herein. We have also made such investigations of law as we have deemed
appropriate as a basis for the opinions expressed below. As to all matters of
fact material to such opinions, we have relied upon the representations of
officers of the Company and the Trustee. We have assumed (i) the genuineness of
all signatures, (ii) the legal capacity of all natural persons, (iii) the
authenticity and completeness of all documents submitted to us as originals,
(iv) the conformity with authentic original documents of all documents submitted
to us as copies, and (v) as to the forms of all documents in respect of which
forms were filed with the Commission or incorporated by reference as exhibits to
the Registration Statement, the conformity in all material respects of such
documents to the forms thereof that we have examined.

         In conducting our examination of documents, we have assumed that (A)
all parties thereto other than the Company (i) had the power, corporate or
other, to enter into and perform their respective obligations thereunder, (ii)
have duly authorized such documents by all requisite action, corporate or other,
and duly executed (or, in the case of the Trustee in respect of the ZYP-CODES,
authenticated) and delivered such documents, and that such documents constitute
valid and binding obligations of such parties, (B) except as to the Company with
respect to the Federal laws of the United States, the laws of the

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State of New York and the Delaware General Corporation Law, all parties to such
documents have obtained all requisite third party and governmental consents,
authorizations and approvals, and made all registrations and filings, necessary
to execute and deliver, and perform their respective obligations under, such
documents, and (C) the execution, delivery and performance of such documents do
not and will not, violate, or require any consent under, the organic documents
of any party thereto (other than the certificate of incorporation and by-laws of
the Company) or any law, rule, regulation, consent, order, writ, injunction or
decree, or any agreement, indenture or other contractual restriction, applicable
to any such person. As to any facts material to the opinions expressed herein
which were not independently established or verified, we have relied upon oral
or written statements and representations of officers, trustees and other
representatives of the Company and others.

         Based upon and subject to the foregoing and subject also to the other
qualifications and limitations set forth herein, and having due regard for such
legal considerations as we deem relevant, we are of the opinion that:

         1. The ZYP-CODES have been duly authorized, executed, issued and
delivered, and the ZYP CODES constitute valid and legally binding obligations of
the Company, enforceable against the Company in accordance with their terms and
entitled to the benefits of the Indenture, except as may be limited by the
effect of (i) bankruptcy, insolvency, reorganization, moratorium (including,
without limitation, all laws relating to fraudulent transfers), or other similar
laws now or hereafter in effect relating to or affecting creditors' rights
generally, and (ii) general principles of equity including, without limitation,
reasonableness, materiality, good faith and fair dealing (regardless of whether
considered in a proceeding at law or in equity).

         2. The Shares initially issuable upon conversion of the ZYP-CODES have
been duly and validly authorized and reserved for issuance and, when issued and
delivered in accordance with the provisions of the ZYP-CODES and the Indenture,
will be duly and validly issued and fully paid and non-assessable.

         This opinion speaks only as of its date and we assume no obligations to
update this opinion should circumstances change after the date hereof. We
express no opinion other than as to the laws of the State of New York, the
General Corporation Law of the State of Delaware (including the applicable
provisions of the Delaware Constitution and the reported judicial decisions
interpreting those laws) and, to the extent applicable, the Federal laws of the
United States. We hereby consent to the filing of this opinion as an exhibit to
the Registration Statement and to the reference to this firm under the heading
"Legal Matters" in the prospectus contained in the Registration Statement. In
giving this consent we do not admit that we are "experts" under the Act, or the
rules and regulations of the Commission issued thereunder, with respect to any
part of the Registration Statement, including this exhibit.

                                            Very truly yours,

                                            /s/ ANDREWS & KURTH L.L.P.

                                            Andrews & Kurth L.L.P.