Between April, 1986 and July, 1991, 477 patients underwent open heart surgery with hypothermic cardiopulmonary bypass. There were 242 patients [50.7%] of acyanotic congenital anomalies, 34 patients [7.1%] of cyanotic congenital anomalies, and 187 patients [39.2%] of acquired heart diseases, 8 patients [1.7%] of coronary artery diseases, and 6 patients [1.3%] of mixed anomalies. Among the 276 congenital cardiac anomalies, 147 patients [53.3%] were male and 129 patients [46.7%] were female, ranged in age from 2 years to 58 years. Among the 187 acquired heart diseases, 72 patients [38.5%] were male and 115 patients [61.5%] were female, ranged in age from 10 years to 68 years. The common congenital defect were VSD and ASD in acyanotic cardiac patients, and TOF in cyanotic cardiac patients. Among the 187 acquired heart diseases, 180 patients underwent operation for cardiac valvular diseases, 4 patients were resected left atrial myxoma, and 3 patients underwent operation for aortic regurgitation with ascending aortic aneurysm. The operative mortality rate was 1.2% in acyanotic cardiac patients, 11.8% in cyanotic cardiac patients, and 6.9% in acquired cardiac patients, with overall mortality rate 4.2%.