From February 1984 through July 1991, 104 infants less than 1 year of age with congenital heart defects underwent open heart repair with conventional cardiopulmonary bypass which occupied 10.7% of all patients with congenital heart defects operated on during same period. There were 66 boys and 38 girls 7 days to 12 months [mean age, 8.2 months]. Four patients were neonates, 8 were 1 to 3 months, 23 were 4 to 6 months, and 69 were 7 to 12 months of age. Mean body weight at repair was 6.9kg and mean BSA, 0.36m2 Indications for operation were intractable congestive heart failure and severe pulmonary hypertension in patients with VSD and severe cyanosis and anoxic spells in patients with TOF. Conditions corrected were VSD[79], TOF[8], AVSD[4], PS[2], PA+IVS[2], TAPVC [2], MR[2], DOLV[l], Truncus arteriosus[1], D-TGA[1], and PA-VSD[1]. Twenty-three of 79 patients with VSD had associated cardiovascular anomalies which included PDA in 16 patients, PS in 9 patients, ASD in 5 patients, LSVC in 2 patients, MR in 1 patient, dextrocardia in 1 patient, and single coronary artery in 1 patient. The hospital mortality rate was 24.0% which was much higher than that of 6% in patients over 1 year of age. The greatest mortality occurred in babies of low weight under 6 months of age, There was no late death. Surviving infants showed marked symptomatic improvement and change in growth patterns. These surgical results were to be overcome with proper pre- and postoperative management and improvement of surgical technique