From May 1977 to June 1986, 500 cases of open heart surgery were performed under the cardiopulmonary bypass. There were 278 male and 222 female patients ranging from 6 months to 69 years. 363 cases[73.6%] were congenital heart diseases, and 137 cases[27.4%] were acquired heart diseases, which were 33 valvular diseases, 3 myxomas and 1 IVC obstruction. There were 363 congenital heart anomaly with 35 operative deaths[9.6%], consisting of 279 acyanotic cases with 12 deaths [4.3%] and 85 cases of cyanotic cases with 23 deaths[28.4%]. In 133 patients of acquired valvular disease, 124 valves were implanted and operative death of valvular disease was 12%. Finally the operative mortality was 9.6% in congenital anomaly, and 12.4% in acquired heart disease, overall mortality rate was 10.4%.