Although the hemodynamic characteristics and durability of the St. Jude valve prosthesis have been reported, the need for and the degree of anticoagulation in patients who receive these valves remain uncertain. Our 10-year experience with 165 patients (100 men and 65 women, mean age of 58 +/- 13 years), who underwent valve replacement with St. Jude prostheses, is reported. Of the 165 patients, 147 were treated with warfarin. A prothrombin time 1.3 to 1.8 times control (range 15 to 20 seconds) was maintained in 134 patients with single valve and 1.8 to 2 times control (range 20 to 25 seconds) in 13 patients with double valve prostheses. The 10-year actuarial event-free incidence from thromboembolic and hemorrhagic complications was 84 and 95%, respectively. Of the 8 patients receiving antiplatelet therapy alone, 4 had thromboembolic events. Of the 10 patients on neither warfarin nor antiplatelet therapy, 3 had thromboembolic events. The 10-year actuarial event-free incidence from valve failure was 95%. The 10-year actuarial patient survival was 55%. Thus, the St. Jude valve is a safe and reliable prosthesis with acceptable overall long-term performance in patients given a modest anticoagulation regimen. Patients who receive St. Jude prosthetic valves without anticoagulants have a high incidence of thromboembolic events despite therapy with antiplatelet agents.