Exhibit 23.1

                         CONSENT OF INDEPENDENT AUDITORS

We consent to the  incorporation  by  reference  in the  following  Registration
Statements:  (i) Form  S-8  (No.33-52148)  pertaining  to the  Ultramar  Diamond
Shamrock  Corporation  1992  Long-Term  Incentive  Plan,  (ii) Form S-8 (No. 33-
62894) pertaining to the Ultramar Diamond Shamrock Corporation  Restricted Share
Plan for  Directors,  (iii) Form S-8 (No.  333-19131)  pertaining to the Diamond
Shamrock,  Inc. 1987  Long-Term  Incentive Plan and the Diamond  Shamrock,  Inc.
Long-Term  Incentive  Plan,  (iv)  Form  S-3  (Nos.   333-28737  and  333-46775)
pertaining to the universal  shelf  registration  of Ultramar  Diamond  Shamrock
Corporation,  (v) Form S-8 (No.  333-27697)  pertaining to the Ultramar  Diamond
Shamrock  Corporation  Non-Employee  Director  Equity  Plan,  (vi) Form S-8 (No.
333-27699)   pertaining  to  the  Ultramar  Diamond  Shamrock  Corporation  1996
Long-Term  Incentive  Plan,  (vii) Form S-8 (No.  333-27701)  pertaining  to the
Ultramar Diamond Shamrock Corporation 401(k) Retirement Savings Plan, and (viii)
Form S-8 (No. 333-27703) pertaining to the Ultramar Diamond Shamrock Corporation
Non-Qualified  401(k) Plan of our report dated  February 7, 1997 with respect to
the consolidated  financial statements and schedule of Ultramar Diamond Shamrock
Corporation  (formerly  Ultramar  Corporation)  for the years ended December 31,
1996 and 1995  included  in the  Annual  Report  (Form  10-K) for the year ended
December 31, 1997 filed with the Securities and Exchange Commission.

                                           /s/ ERNST & YOUNG LLP

San Antonio,  Texas
March 16, 1998