Ten patients with aortic regurgitation underwent aortic valve replacement using a Björk-Shiley valve prosthesis. They ranged from 27 to 58 years of age. The studies were centered around the postoperative hemodynamics, especially concerning the function of the left ventricle during a follow-up period which averaged about 8 months. The left ventricular end-diastolic volume (LVEDV) returned to the normal range, and the muscle mass of the left ventricle decreased remarkably after surgery. The ejection fraction and mean velocity of the circumferential fiber shortening both increased up to the normal range. The left ventricular end-diastolic pressure exhibited normal values with a decrease of the LVEDV. The depressed left ventricular function was largely reversible after surgery.