100 cases of open heart surgery were done in the Dept. of Thoracic and Cardiovascular Surgery, Won Kwang University Hospital from July, 1984 to October, 1986. l. Among the 100 cases, there were 51 cases [51%] of acyanotic congenital heart anomalies, 10 cases [10%] of cyanotic congenital heart anomalies and 39 cases [39%] of acquired heart disease. 2. The age distribution of 100 cases was 18 months to 56 years old and mean age was 10.8 years old in congenital heart anomalies and 34.7 years old of acquired heart disease. 3. The overall mortality was 8%. and the mortality in each entity is 5.9% in congenital acyanotic cases, 10% in congenital cyanotic cases and 10.3% in acquired valvular heart disease. 4. For myocardial protection, high concentration potassium of cold blood cardioplegic solution [30mEq/L] had been used, associated with topical cooling of ice-slush.