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, 333-28737-02,
333-28737-04, 333-46775, 333-46775-01 and 333-46775-02) pertaining to the
universal shelf registration of Ultramar Diamond Shamrock Corporation, UDS
Capital II and UDS Funding II, L.P., (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 statements of operations,
stockholders' equity, cash flows and comprehensive income (loss) of Ultramar
Diamond Shamrock Corporation (formerly Ultramar Corporation) for the year ended
December 31, 1996 included in this Annual Report (Form 10-K) for the year ended
December 31, 1998 filed with the Securities and Exchange Commission.
 
                                                          /s/ Ernst & Young LLP
 
San Antonio, Texas
March 29, 1999