A group of 80 patients were studied retrospectively to determine whether preoperative echocardiography is useful in predicting operative results in patients with aortic valve replacement for chronic aortic insufficiency. One year after operation, percent change of left ventricular dimension (%delta D) and ejection fraction (EF) were higher and end-systolic left-ventricular internal dimension was smaller in patients with good results than in those who had poor results (p less than 0.05). Regarding probability of 5 year survival, patients with a %delta D of more than 35% had good prognosis, those with 31% to 35% had a fairly good prognosis, and those with 30% or less had increased risk of death, especially if they were in New York Heart Association (NYHA) Functional Class III or IV. All deaths occurred in patients with preoperative values of 31% or less. Patients with EF of 60% or more had a better prognosis than those with a value of less than 60%. In addition, 10 early postoperative echocardiographic studies showed no correlation between early regression of end-diastolic left ventricular internal dimension and long-term operative results; 18 late postoperative studies showed reduction in this dimension in patients with good surgical results, and the only one with a poor result had an enlarged dimension. Thus echocardiographic indices of left ventricular function (%delta D) and EF) may be useful as prognostic indicators in patients undergoing aortic valve replacement for aortic insufficiency.