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                                                                  EXHIBIT 5.1(a)


                             Andrews & Kurth L.L.P.
                             600 Travis, Suite 4200
                              Houston, Texas 77002

                                                              July 30, 2001

Board of Directors
Anadarko Finance Company
Anadarko Petroleum Corporation
17001 Northchase Drive
Houston, Texas 77060-2141

           Re:  Anadarko Finance Company and Anadarko Petroleum Corporation;
                Registration Statement on Form S-4.

Gentlemen:

         We have acted as special counsel to Anadarko Finance Company, an
unlimited liability company organized under the laws of the Province of Nova
Scotia, Canada ("Anadarko Finance"), and a wholly-owned, indirect subsidiary of
Anadarko Petroleum Corporation, a Delaware corporation ("Anadarko Petroleum" and
together with Anadarko Finance, the "Obligors"), in connection with the public
offering of (i) $950,000,000 aggregate principal amount of Anadarko Finance's 6
3/4% Series B Senior Notes due 2011 (the "10-Year Exchange Notes") and (ii)
$900,000,000 aggregate principal amount of Anadarko Finance's 7 1/2% Series B
Senior Notes due 2031 (the "30-Year Exchange Notes" and, together with the
10-Year Exchange Notes, the "Exchange Notes"). The Exchange Notes are to be (i)
issued under the Indenture, dated as of April 26, 2001, as amended by a
supplemental indenture dated May 23, 2001 (such indenture as supplemented being
referenced herein as the "Indenture"), by and among the Obligors and The Bank of
New York, as trustee (the "Trustee"), and (ii) fully and unconditionally
guaranteed by Anadarko Petroleum pursuant to a guarantee (the "Guarantee")
included in the Indenture. The Exchange Notes are to be issued pursuant to an
exchange offer (the "Exchange Offer") by Anadarko Finance to the holders of its
issued and outstanding 6 3/4% Series A Senior Notes due 2011 (the "10-Year
Original Notes") and the holders of its issued and outstanding 7 1/2% Series A
Senior Notes due 2031 (the "30-Year Original Notes" and, together with the
10-Year Original Notes, the "Original Notes"), pursuant to which Exchange Offer,
Anadarko Finance is offering to exchange (i) the 10-Year Exchange Notes for a
like principal amount of issued and outstanding 10-Year Original Notes and (ii)
the 30-Year Exchange Notes for a like principal amount of issued and outstanding
30-Year Original Notes, all as contemplated by the Registration Rights
Agreement, dated as of April 26, 2001 (the "April Registration Rights
Agreement"), by and among the Obligors and Credit Suisse First Boston
Corporation ("CSFB"), and the Registration Rights Agreement, dated as of May 23,
2001 (the "May Registration Rights Agreement" and together with the April
Registration Rights Agreement, the "Registration Rights Agreements"), by and
among the Obligors and CSFB.

         This opinion is being furnished in accordance with the requirements of
Item 601(b)(5) of Regulation S-K under the Securities Act of 1933, as amended
(the "Act").


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Board of Directors
Anadarko Finance Company
Anadarko Petroleum Corporation
July 30, 2001
Page 2

         In connection with this opinion, we have examined originals or copies,
certified or otherwise identified to our satisfaction, of:

         (a) the registration statement on Form S-4 (Registration No.
333-65082), filed by the Obligors with the Securities and Exchange Commission
(the "SEC") on July 13, 2001, and Amendment No. 1 to such Registration
Statement, filed with the SEC on July 30, 2001 (such registration statement, as
so amended, being hereinafter referred to as the "Registration Statement");

         (b)  Anadarko Petroleum's Certificate of Incorporation and By-laws,
              each as amended to date;

         (c)  an executed copy of the Indenture;

         (d)  executed copies of each of the Registration Rights Agreements;

         (e)  the Form T-1 of the Trustee filed as an exhibit to the
              Registration Statement;

         (f)  the form of the 10-Year Exchange Notes; and

         (g)  the form of the 30-Year Exchange Notes.

         We have also examined originals or copies, certified or otherwise
identified to our satisfaction, of such records of the Obligors and such
agreements, certificates of public officials, certificates of officers or other
representatives of the Obligors and others, and such other documents,
certificates and records as we have deemed necessary or appropriate as a basis
for the opinion set forth herein.

         In our examination, we have assumed, without independent investigation,
the legal capacity of all natural persons, the genuineness of all signatures on
all documents that we have examined, the authenticity of all documents submitted
to us as originals, the conformity to original documents of all documents
submitted to us as certified, conformed or photostatic copies and the
authenticity of the originals of such latter documents. In conducting our
examination of executed documents or documents to be executed, we have assumed,
without independent investigation, that all parties thereto, other than Anadarko
Petroleum, had or will have the power, corporate or other, to enter into and
perform all obligations thereunder and have also assumed, without independent
investigation, the due authorization by all requisite action, corporate or
other, and execution and delivery by such parties of such documents and, except
as set forth below with respect to the Obligors, the validity and binding effect
thereof on such parties. As to any facts material to the opinion expressed
herein which we have not independently established or verified, we have relied
upon oral or written statements and representations of officers and other
representatives of the Obligors and others.


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Board of Directors
Anadarko Finance Company
Anadarko Petroleum Corporation
July 30, 2001
Page 2


         Our opinion set forth herein is limited to the laws of the State of New
York that are normally applicable to transactions of the type contemplated by
the Exchange Offer and to the extent that judicial or regulatory orders or
decrees or consents, approvals, licenses, authorizations, validations, filings,
recordings or registrations with governmental authorities are relevant, to those
required under such laws (all of the foregoing being referred to as
"Opined-on-Law"). We do not express any opinion with respect to the law of any
jurisdiction other than Opined on Law or as to the effect of any such other law
on the opinion stated herein.

         Based upon and subject to the foregoing, having due regard for such
legal considerations as we deem relevant, and subject to the limitations,
qualifications, exceptions and assumptions set forth herein, we are of the
opinion that when the Exchange Notes (in the form examined by us) have been duly
executed by Anadarko Finance, authenticated by the Trustee in accordance with
the terms of the Indenture and delivered upon consummation of the Exchange Offer
against receipt of Original Notes surrendered in exchange therefor in accordance
with the terms of the Exchange Offer, the Registration Rights Agreement and the
Indenture, (1) the Exchange Notes will constitute valid and binding obligations
of Anadarko Finance, enforceable against Anadarko Finance in accordance with
their terms, and (2) the Guarantee will constitute a valid and binding
obligation of Anadarko Petroleum, enforceable against Anadarko Petroleum in
accordance with its terms, except, with respect to clauses (1) and (2) above,
(a) to the extent that enforcement thereof may be limited by (i) bankruptcy,
insolvency, reorganization, moratorium, fraudulent conveyance or other similar
laws now or hereafter in effect affecting creditors' rights generally and (ii)
general principles of equity (regardless of whether enforceability is considered
in a proceeding at law or in equity), and (b) we express no opinion regarding
the enforceability or effect of Section 3.06 of the Indenture.

         In rendering the opinion set forth above, we have assumed that the
execution and delivery by Anadarko Finance of the Indenture and the Exchange
Notes, the execution and delivery by the Guarantor of the Indenture and the
notations on the Exchange Notes relating to the Guarantee, the performance by
each of the Obligors of its obligations under the Indenture and the Exchange
Notes, do not and will not violate, conflict with or constitute a default under
any agreement or instrument to which either Obligor or its properties is
subject. In addition, we have assumed that Anadarko Finance is validly existing
and in good standing under the laws of its jurisdiction of organization and has
complied with all aspects of such laws in connection with the issuance of the
Exchange Notes and the related transactions. Also, our opinion set forth above
is subject to possible judicial action giving effect to foreign governmental
actions or foreign laws affecting creditors' rights.

         We hereby consent to the filing of this opinion with the SEC as an
exhibit to the Registration Statement. We also consent to the reference to our
firm under the caption "Legal Matters" in the Registration Statement. In giving
this consent, we do not thereby admit that we are included in the category of
persons whose consent is required under Section 7 of the Act or the rules and
regulations of the SEC. This opinion is expressed as of the date hereof, and we
disclaim any undertaking to advise you of any subsequent changes in the facts
stated or assumed herein or of any subsequent changes in applicable law.

                                       Very truly yours,

                                       /s/ ANDREWS & KURTH LLP.