Between October, 1978, and December, 1982, Glutaraldehyde-stablized pericardial xenografts [Ionescu-Shiley valve] were used for heart valve replacement in 409 patients.[251 mitral, 49 aortic, 11 tricuspid, and 98 multiple valve replacement]. There were 31 early deaths [7.6%], and 371 operative survival were observed for a total of 507.6 years over a period of 1 to 44 months. [mean 17 months]. Actuarial analysis of late results indicates an excepted survival rate at 4 years of 86.25.4% for patients with mitral, 79.37.1% for patients with aortic valve replacement. Actuarial survival rates for total patients at 4 years was 77.88.2%. The rate of systemic embolism has been 1.6% per patient-year for mitral and 1.8% per patient-year for aortic group in the presence of anticoagulation treatment. Among the 6 embolic episodes, 2 patients were died. The incidence of hemorrhagic complication was 1.3% per patient-year for anticoagulated patients. There were 6 confirmed valve failures, five in mitral and one in aortic position. Re-replacement of destructed valve was performed in one patient and others were treated medically. Among the 6 episodes, 3 occurred in children [Below 15 years], it account almost 9 times higher than adult. Our clinical data compare very favorable with those obtained with other available prostheses and tissue valves, but it should be considered to give short-term anticoagulation therapy to hemodynamically stable patients and aortic valve patients, and other prosthetic valve must be considered to use in children. [KTCS 1983;4:458-469]