From August 1977 to August 1982, aortic valve replacement (AVR) with the Ionescu-Shiley pericardial valve was carried out on 172 patients. Hospital mortality was 4.3% for solitary AVR and 15% for patients with additional surgery. The expected 5 year survival rate was 96.7% for patients with isolated AVR and 81.8% for associated AVR. Cumulative duration of follow-up was 3,892 patient-months (mean 26.8 months per patient). The actuarial projection of freedom from thromboembolic episodes was 98.6% for isolated AVR and 91.6% for associated AVR. Seven patients underwent reoperation: 4 for infective endocarditis, 1 for massive perivalvular leak, 2 for primary tissue failure. Although the actuarial rate of freedom from valve failure for isolated AVR with Ionescu-Shiley valve was 93.7% at 5 years after surgery, the next few years of follow-up will be critical in determining the superiority of this valve over the porcine bioprostheses.