Exhibit 5.1

December 31, 1996



Ultramar Diamond Shamrock Corporation
9830 Colonnade Boulevard
San Antonio, Texas 78230

Re:  Registration Statement on Form S-8 of Ultramar Diamond Shamrock
     Corporation (Registration No. ______________)

Gentlemen:

I am a Senior Attorney of Ultramar Diamond Shamrock Corporation (the
"Company").  This letter is delivered in connection with the registration,
issuance, and sale of up to an aggregate amount of 1,000,000 shares of
Common Stock (the "Offered Securities") pursuant to the resolutions
authorizing the issuance and sale of the Offered Securities, and such other
acts as are necessarily incident to the registration, issuance and sale of
the Offered Securities (the "Authorizing Resolutions") adopted by the
Company's Board of Directors at a meeting of the Company's Board of
Directors held on September 22, 1996. 

I have examined such documents, records, and matters of law as I have
deemed necessary for the purposes of this opinion, and based thereon I am
of the opinion that the Offered Securities have been duly authorized and
will be valid and binding obligations of the Company (except as enforcement
thereof may be  limited by bankrupcy, insolvency, fraudulent conveyance, 
reorganization, moratorium, and other similar laws relating to or affecting
creditors' rights generally and subject to general equitable principles)
when the Offered Securities are issued, authenticated or countersigned, and
delivered by the Company for valid consideration in accordance with the
Authorizing Resolutions and the Company's Certificate of Incorporation (the
"Certificate").

This opinion is based on the Company's Certificate and Bylaws and
applicable law as of the date hereof.  No assurance can be provided as to
the effect on this opinion of any amendment or other change to the
Company's Certificate or Bylaws or applicable law after the date hereof.

I hereby consent to the filing of this opinion as an exhibit to the
Registration Statement on Form S-8 filed by the Company to effect
registration under the Securities Act of 1933, as amended, of the Offered
Securities and to the reference to me under the caption "Legal Matters" in
the Prospectus comprising part of such Registration Statement.

Very truly yours,

/s/ TODD WALKER


    TODD WALKER

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