A total and consecutive 62 patients between 13 and 58 years of age receiving biological prosthetic heart valves at the Korea University Hospital from January 1978 through October 1983 were analyzed. Out of 71 valves replaced, 64 were Carpentier-Edwards valves, 4 were Ionescu-Shiley valves, 2 were Angell-Shiley valves, 1 was Hancock valve. Early mortality within 30 days after operation was noted in 4 cases[6.4%]. There were no cases of valve-related early death. The 58 early survivors were followed-up for a total 387 patient-year over a period of 3 years to 12 years[Mean$pm$S.D: 6.37$pm$2.51 years] at the follow-up end of April 1991. During follow-up, seven patients died and late mortality rate was 12%. There were two major late complications: the one is thromboembolism[1.6% /patient-year], the other is primary tissue failure[2.76% /patient-year]. Ten patients underwent re-replacement of 13 tissue valves because of primary tissue failure[nine Carpentier-Edwards, two Ionescu-Shiley, two Angell-Shiley]. There was operative mortality. The probabilities of freedom from primary tissue failure were 95.4% and 75.3% at 5 and 10 years after operation respectively, The actuarial survival rates were 86.2% and 81.8% at 5 and 10 years after initial surgery respectively.