The first 50 cases at the Mayo Clinic of insertion of an aortic valvular homograft after excision of the aortic valve are reported. The hospital mortality rate was 6%. An aortic diastolic murmur was noted in 17% of the surviving patients just prior to their dismissal from the hospital. In none was there evidence of hemodynamically significant aortic valvular incompetence. At follow-up examination 3 to 12 months postoperatively, an aortic diastolic murmur was audible in 44% of the traced patients. Only one patient had hemodynamically significant aortic valvular incompetence. The patients were not given anticoagulant therapy, and there were no thromboembolic complications.