Exhibit 12.1 ULTRAMAR DIAMOND SHAMROCK CORPORATION COMPUTATION OF RATIO OF EARNINGS TO FIXED CHARGES (dollars in millions, except ratios) Three Months "Ended "Year Ended December 31," March 31," 1996 1995 1996 1995 1994 1993 1992 Earnings: Income before taxes 45.8 36.8 37.2 (1) 141.1 220.7 197.3 133.4 Add: Fixed Charges 36.2 35.6 141.3 151.6 108.6 118.0 120.1 Amortization of interest previously capitalized 0.3 0.2 Losses of investees 0.5 1.1 Less: Capitalized interest (1.1) (5.8) (10.6) (16.4) (7.8) (6.1) (6.1) Undistributed earnings of investees (0.2) Earnings as adjusted 80.9 66.6 168.2 277.0 321.5 309.0 248.5 Computation of Fixed Charges: Interest expense 30.1 24.8 110.1 113.9 87.1 93.1 93.5 Capitalized interest 1.1 5.8 10.6 16.4 7.8 6.1 6.1 Interest portion of lease commitments 5.0 5.0 20.6 21.3 13.7 18.8 20.5 Total Fixed Charges 36.2 35.6 141.3 151.6 108.6 118.0 120.1 Ratio of Earnings to Fixed Charges (2) 2.2 1.9 1.2 1.8 3.0 2.6 2.1 (1) Excludes merger and integration costs of $77.4 million. (2) For the purpose of calculating the ratio of earnings to fixed charges, "earnings as adjusted" consist of income before income taxes after adding certain fixed charges as noted above. "Fixed charges" consist of interest expense, amortization of debt discount and a portion of rent expense representative of the interest factor. W5120.tw