From Sep. 1985 to Dec. 1992, total 1000 cases of open heart surgery [OHS] were performed in the department of Thoracic & Cardiovascular Surgery, Pusan Paik Hospital, College Of Medicine, Inje University.Among the total 1,000 cases of OHS, there were 823 cases with congenital heart diseases [CHD] and 177 cases with acquired heart diseases [AHD]. The age distribution was 9 days [4.0 kg] to 49 years in CHD and 11 to 64 years in AHD, In the 823 cases of CHD, there were 763 acyanotic cases and 60 cyanotic cases. The CHD cases consisted of 520 VSD [63.2 %], 177 ASD [21.5 %], 60 TOF[7.3 %], 27 PS [3.3 %], 17 ECD [2.1%], 7 Valsalva sinus rupture [0.9 %], 4 TGA [0.5 %], 3 Ebstein`s anomaly [0.4%], 3 DORV[0.4%], and others. The corrective operations were applied for congenital heart disease with the result of 2. 8 % hospital mortality. In the 177 AHD, 168 cases were valvular heart diseases, 7 cases were cardiac tumors and one LA thrombus and one annuloaortic ectasia. In the 168 valvular heart diseases, there were 115 single valve replacement cases [16 AVR, 99 MVR], 20 cases of double valve replacement[AVR & MVR], 15 cases of MVR with TVA, and 10 cases of AVR, MVR with TVA. The total implanted prosthetic valves were 199`. In MVR, 66 of St. Jude Medical valves, 78 ofCarpentier-Edward valves, and 5 of Ionescu-Shiley valves were used. In AVR, 38 of St. Jude Medical valves and 12 of Carpentier-Edward valves were used.The hospital operation mortality rate of congenital acyanotic, cyanotic, and acquired heart diseases were 1.6%, 18.3 % and 3.4% respectively. The overall mortality rate was 2.9 % [29/1000].