Between March, 1988 and July, 1992, 114 patients underwent Open Heart Surgery under hypothermic cardiopulmonary bypass. There were 29 cases of congenital heart anomalies (25％), and 85 cases of acquired heart diseases (75％) consisting of 53 cases of valvular heart disease, 31 cases of ischemic heart disease, and a case of left atrial myxoma. The age distribution of 114 cases was 4 to 73 years, and mean age was 43 years old consisting of mean age of congenital heart disease 23, valvular heart disease 47, and ischemic heart disease 57 years old. Overall operative mortality was about 7.9％.