We reviewed our 12-year experience with 254 adult patients who had St. Jude valves in the aortic position and used multivariate analysis to examine risk factors possibly affecting long-term morbidity and mortality. Nineteen-millimeter or 21-mm valves were implanted in 115 patients. Poor preoperative congestive heart failure status was associated with persistent congestive heart failure on late follow-up. Preoperative congestive heart failure and coronary artery disease were the only predictors of overall late death. Late deaths associated with heart failure and late sudden deaths were examined separately. Preoperative degree of heart failure was the only predictor of late death with associated heart failure. The implantation of a 19- or 21-mm valve in patients with a body surface area greater than 1.9 m2 somewhat increased the risk of late sudden death. In patients with a body surface area greater than 1.9 m2 and with a 19-mm or 21-mm annulus, consideration should be given to using a high-performance St. Jude valve or performing an annulus-enlarging procedure if this can be done with negligible morbidity.