During the full 10-year period from June 1968 through June 1978, 112 consecutive patients underwent isolated or double valve replacement. A total of 130 valves were used in aortic, mitral or tricuspid positions: 63 prosthetic valves in 56 and 67 glutaraldehyde-preserved porcine aortic valves in 56 patients. There were 31 early and 9 late deaths with a cumulative mortality rate of 35.7 percent. Eighty-five patients survived longer than 10 days postoperatively were studied for the occurrence of thromboembolism and complications related to anticoagulant therapy. At the end of follow-up period, 68 patients were on Coumadin; 74 were on Persantin with or without Coumadin; 11 were off any antithrombotic drugs with 6 of them being off electively after 6 months of tissue valve replacement. Thromboembolism occurred in 7 [8.2%] of 85 patients or 10.9%/patient-year. Embolic rates were as follows: one of 18 patients anticoagulated [5.6%] or 6.1%/patient-year and 4 of 16 patients not anticoagulated [25.0%] or 17.8%/patient-year for the prosthetic valve replacement; and one of 40 patients anticoagulated [2.5%] or 7.9%/patient-year and one of 11 patients not anticoagulated [9.1%] or 7.9%/patient-year for tissue valve replacement. Three complications of major bleeding were experienced by 3 patients during the follow-up period, being related to Coumadin therapy. The importance of proper anticoagulation were stressed for the successful management of patients after cardiac valve replacement, both prosthetic and tissue valves.[KTCS 1978;3:303-315]