Replacement of cardiac valves in the pediatric patients is infrequent compared with in adult for the treatment of diseased heart valve. Furthermore, uncertainties regarding the long term fate of prosthetic value and effects of a fixed-orifice walve in the growing children are the main concern in pedriatric patients. Between January 1974 and October 1979, in 10 children, 15years or younger, cardiac valves were replaced becasuse of congenital or acquired valvular heart diseases in the Department of Thoracic & Cardiovascular Surgery, Seoul National University Hospital. There were 8 mitral valves, one aortic valve and one mitral and aortic valve replaced. Indications for valve replacement were intractable congestive heart failure or apperently progressing cardiac symptoms and signs. Early postoperative death was noticed in one due to arrythmia, and late postoperative death in one due to cerebral thromboembolism after 9 months of double valve replacement. All Survlvors showed clinical improvement and good cardiac condition during postoperative and follow-up period till now.