This study assesses the long-term (mean 52+/-24 months) performance of the St. Jude Medical (SJM) valve in 200 young (mean age 31+/-13 years) rheumatic patients on low-level warfarin anticoagulation combined with dipyridamole. Follow-up was 95% complete and comprised 867 patient-years. There were 33 deaths (3.8%/patient-year). Death was valve related in 12 cases and due to left ventricular dysfunction in 10. Death due to left ventricular dysfunction occurred earlier after surgery than death due to other causes (10+/-7 vs 29+/-18 months, p <0.005); these patients had larger preoperative left ventricular dimensions than the rest of the group (end-systolic diameter 51+/-13 vs 37+/-16 mm, end-diastolic diameter 66+/-13 vs 50+/-19 mm, p = 0.006). Actuarial probability of survival was 81% at 86 months and probability of event-free survival was 71%. The median international normalized ratio was 1.88+/-0.54. Thromboembolism (13 events) occurred at a linearized rate of 1.5%/patient-year. There were 11 major bleeding episodes (1.3%/patient-year), 4 cases of prosthetic valve endocarditis (0.8%/patient-year), and 12 paraprosthetic leaks (1.4%/patient-year). No valve obstructions or reoperations occurred. Thus, the SJM valve performs well on low-level anticoagulation combined with dipyridamole. Left ventricular dysfunction was a common cause of death in the early postoperative period.