Left ventricular systolic and diastolic function and mass index was charted prospectively in 46 patients with aortic stenosis with serial measurements at eight days, three months and 18 months after valve replacement. Left ventricular response to the operation was predictable. A significant reduction in hypertrophy occurred over the first 18 postoperative months, but to a normal ventricular mass in only a minority of patients. Insufficient regression of hypertrophy was related to indices of irreversible myocardial disease which also prevented functional ventricular improvement, despite a successful valve replacement and a hemodynamically well-functioning valve.