One hundred eleven cases of open heart surgery had been performed at the department of thoracic and cardiovascular surgery in College of Medicine Hallym Univ. from November 28, 1984 to August, 1991. There were 68 cases of congenital heart disease and 43 cases of acquired heart disease. Among the 68 cases of congenital heart diseases, 65 cases of acyanotic group and 3 cases of cyanotic group were noted. The majority of acquired heart diseases were valvular heart disease. The congenital heart disease consisted of 33 ASD, 27 VSD, 6 PS, 3 TOF. The sex ratio of congenital and acquired heart diseases was represented as 1.4: 1 and 1; 1.4 respectively. The age distribution of congenital heart diseases ranged from 11 months to 50 years old and that of acquired heart diseases from 15 to 61 years old. The overall operation mortality was 1 case[0.9%].