610 cases of open heart surgery was performed in the Department of Thoracic and Cardiovascular Surgery, Pusan National University Hospital from July 1981 to September 1987. The clinical data was summarized as follows: 1. The age distribution of congenital heart surgery patients was 2 to 41 years old [mean; 13.2 years] and surgery for acquired heart disease was 10 to 57 years old [mean: 32.8 years]. 2. There were 389 cases [63.8%] of acyanotic congenital heart anomalies, 63 cases [10.3%] of cyanotic congenital anomalies and 158 cases [25.9%] of acquired heart disease. 3. For myocardial protection, Bretschneider and potassium glucose solution had been used as cardioplegic solution and then since 1983, GIK solution has been used with repeated infusion method once for every 20 to 30 minutes of time interval after starting initial cardioplegia during operation with excellent results. 4. The ingredient of the priming solution is Hartmann`s solution, sodium bicarbonate, mannitol, potassium chloride, fresh ACD whole blood, calcium chloride, heparin and dexamethasone. 5. There were 96 cases [15.7%] of mild hypothermia, 333 cases [54.6%] of moderate hypothermia and 181 cases [29.7%] of intermediate hypothermia. 6. The mortality rate was 2.3% [9 out of 389 cases] in acyanotic congenital heart disease, 36.5% [23 out of 63 cases] in cyanotic congenital heart disease and 10.8% [17 out of 158 cases] in acquired heart disease, with overall mortality rate of 8.0% [49 out of 610 cases].