To assess with truly long follow-up the long-term results of valve replacement with the St. Jude Medical prosthesis (St. Jude Medical, Inc., St. Paul, Minn.), we reviewed the case histories of the first 1112 patients undergoing 1244 valve replacements with this valve between June 12, 1978, and June 12, 1987: 690 male (62%) and 422 female patients, mean age 56 years. A total of 773 patients (69%) had the aortic valve replaced, 207 (19%) the mitral valve, and 132 (12%) the aortic and mitral valves. There were 42 hospital deaths (3.8%). Follow-up was 97.5% complete (8988 patient-years). There were 213 late deaths. Ninety-one (43%) were considered valve-related: sudden death, n = 27; anticoagulant-related hemorrhage, n = 22; thromboembolism, n = 19; prosthetic valve endocarditis, n = 13; valve thrombosis, n = 9; and noninfectious perivalvular leak, n = 1. Overall actuarial survival, including hospital mortality, was 68% +/- 6% (95% confidence limits) 14 years after the operation. Linearized rates of late valve-related events were as follows: thromboembolism, 1.09% per patient-year; anticoagulant-related hemorrhage, 0.94% per patient-year; prosthetic valve endocarditis, 0.32% per patient-year; valve thrombosis, 0.33% per patient-year; and perivalvular leak, 0.19% per patient-year. Actuarial freedom, at 14 years, from thromboembolism was 89% +/- 3%, anticoagulant-related hemorrhage 83% +/- 8%, valve thrombosis 97% +/- 1%, and reoperation 95% +/- 3%. Actuarial freedom from all valve-related deaths and valve-related morbidity and mortality, at 14 years, was 84% +/- 6% and 61% +/- 8%, respectively. We conclude that, because of its low thrombogenicity, low incidence of valve-related events, and low valve-related mortality, the St. Jude Medical valve is one of the best performing mechanical prosthesis currently available. Nevertheless, the late valve-related complications and deaths illustrate that the quest for a "perfect" prosthesis remains unfulfilled.