EXHIBIT 5.1

February 23, 1998



Ultramar Diamond Shamrock Corporation
6000 North Loop 1604 West
San Antonio, Texas  78249-1112

Re:      Registration Statement on Form S-3 of Ultramar Diamond
         Shamrock Corporation (Registration No. ____________)

Gentlemen:

I am Vice President, General Counsel and Corporate Secretary 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 $700,000,000 of Senior Debt
Securities, Subordinated Debt Securities, Common Stock, Preferred
Stock, and Guarantees (collectively 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 February 4, 1998.  The Senior Debt Securities will be
issued pursuant to the terms of an indenture (the "Senior Debt
Indenture") dated as of March 15, 1995, between the Company and The
Bank of New York acting as trustee (the "Trustee").  The
Subordinated Debt Securities will be issued pursuant to the terms
of an indenture (the "Subordinated Debt Indenture") between the
Trustee and the Company dated June 25, 1997.

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
bankruptcy, 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
(i) in the case of the Senior Debt Securities, the terms of the
Senior Debt Indenture, (ii) in the case of the Subordinated Debt
Securities, the terms of the Subordinated Debt Indenture, (iii) in
the case of Common Stock, the Company's Certificate of
Incorporation, and (iv) in the case of the Preferred Stock, the
relevant Designation of Preferences.

This opinion is based on the Company's Certificate of Incorporation
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 of Incorporation 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-3 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/ Curtis V. Anastasio

Curtis V. Anastasio