During 12 years period from 1974 to 1985, 76 valve replacement procedures were performed at Seoul National University Hospital in 67 pediatric patients aging up to 15 years [mean 12.3 years] and it was 7.3% of total valve replacement procedures in same period. Sixty seven patients were composed of 44 males and 23 females. Of the 67 patients, 43 patients had acquired valve lesions and 24 patients congenital valve lesions. Sixty cases received single valve replacement, 7 cases double or triple valve replacement and 9 cases redo-valve replacement. Sixty seven patients received 84 valves [65 bioprosthetic valves and 19 prosthetic valves by] 76 operations, Sixty three of 65 bioprosthetic valves had been replaced before 1983 and 15 of 19 prosthetic valves in recent 2 years. Eleven patients [14.6%] died within one month post-operatively and 8 patients [10.5%] during the follow-up period with the overall mortality rate of 25.1%. There were early post-operative complication of 23 cases [30.3%] and late post-operative complication of 27 cases [35.3%] with the total complication rate of 65.8%. In 58 patients received bioprosthetic valves, there were 14 cases of restenosis of replaced valves. Of the 14 cases of bioprosthetic valve restenosis, 8 cases received redo-valve replacement procedures without mortality in 1 5/12-5 years after initial operation but 4 cases died without reoperation and 2 cases lost during follow-up. The overall mortality and complication rate were still high but they markedly decreased during recent 2 years. So, in spite of its containing many problems, valve replacement in children is becoming safe and useful procedure in whom valve reconstructive procedures are impossible.