We report 93 cases of severe aortic stenosis. We discuss their clinical data, hemodynamic parameters, and surgical outcome. The surgical mortality and variables determining this event evaluated in groups: A (deaths) and B (survivors). Functional class (mean = 2.5 vs 2.0 p less than 0.05) was statistically as determinant for mortality as were also: transaortic gradient (group A mean = 110 +/- 37 mmHg vs group B mean = 82 +/- 31 p less than 0.005), and ejection fraction (group A mean = 55 +/- 13.7 vs group B mean = 64 +/- 14.8 p less than 0.005). Neither time of cardiopulmonary bypass nor aortic clamping were determinants for mortality. Our results are similar to those reported in other groups. Mortality rates, are determined basically by deterioration of left ventricular function, and by the severity of transaortic gradient.