Three hundred and twenty-six patients underwent CarboMedics valve implantation (CM) in the aortic (119 patients), mitral (148 patients) or aortic and mitral (59 patients) positions while 371 patients underwent St. Jude Medical valve implantation (SJ) in the aortic (113 patients), mitral (184 patient), or aortic and mitral (74 patients) positions at National Taiwan University Hospital from August 1991 through 1995. All patients received warfarin (Coumadin) anticoagulation with the target international normalized ratio around 1.5. The hospital mortality was 3.7% in the CM group and 4.3% in the SJ group. In the CM group at 5 years, the actuarial freedom from thromboembolism, valve thrombosis, and anticoagulant-related hemorrhage was 89.91 +/- 2.66%, 95. 23 +/- 1.50%, and 99.62 +/- 0.37%, respectively, and the actuarial survival rate was 90.4 +/- 1.6%. In the SJ group at 5 years, the actuarial freedom from thromboembolism, valve thrombosis, and anticoagulant-related hemorrhage was 94.79% +/- 1.70%, 98.80 +/- 0.72%, and 99.68 +/- 0.31%, respectively, and the actuarial survival rate was 91.3 +/- 1.7%. We therefore concluded that a similar survival rate was noted in the CM and SJ groups. With low dose anticoagulation, the complications of thromboembolism, valve thrombosis, and anticoagulant-related hemorrhage were low in the SJ group.