From 1985 to 1990, a total of 160 new valves were implanted for 125 adult patients to whom prosthetic valve replacement had been performed [One patient had consecutive 2 reoperations]. Following data are the results from the follow-up study from January 1985 to February 1991. Mean age of the patients was 37.9$pm$12.1 years. Mean follow-up period was 25.8$pm$18.8 months. In bioprosthesis, mean interval between the previous operation and reoperation was 85.6$pm$36.4 months in aortic valve, and 87.3$pm$30.0 months in mitral valve. The causes of reoperation were prosthetic valve failure[103 patients, 81.7%], prosthetic valve endocarditis[17 patients, 13.5%], periprosthetic leakage[5 patients, 4.0%], and aneurysm of ascending aorta[1 patient, 0.8%]. Fourteen patients[11.1%] died in hospital; 5 in 22 replacement of aortic valve[22.7%], 6 in 73 rereplacement of mitral valve[8.2%], and 3 in 31 replacement of multiple valves [9.7%] Except for 3 intraoperative deaths, postoperative, major and minor complications occurred in 39 patients[31.0%]. And the actuarial 5-year survival rate of operative survivors was 95.5$pm$8.6%.