Between February, 1977, and April, 1982, 168 patients underwent aortic valve replacement (AVR) with an Ionescu-Shiley bovine pericardial valve. Concomitant procedures were performed in 71 patients. There were 12 hospital deaths (7.1%). Among patients having AVR only, there were 5 deaths (5.2%). Assessment included valve durability, incidence of thromboembolism, clinical improvement, and patient survival. There was 100% follow-up. Actuarial freedom from intrinsic valve failure at 5 years was 96.3 +/- 3.6%. Intrinsic valve failure occurred only once, 0.3 episodes per 100 patient-years. Four patients had thromboembolic complications. As for clinical status, 99.3% of surviving patients are in New York Heart Association Functional Class I or II, including 79 patients with valve sizes 17, 19, or 21 mm (56%). Among 13 late deaths, 9 were related to the cardiovascular system. Overall patient survival is 84.9 +/- 4.7%. Among the 92 patients with isolated AVR, 87.8 +/- 5.9% are alive at the 5-year follow-up. If the incidence of valve failure is not altered in years to come, the durability of the Ionescu-Shiley bovine pericardial valve will surpass that of previous bioprostheses.