From June 1983 to April 1988, 100 consecutive infants with symptomatic tetralogy of Fallot (without pulmonary atresia) were operated on. Ages ranged from 0.5 to 12 months (mean 7.3 +/- 3.7). Twenty patients were 0.5 to 3 months, 21 were 3 to 6 months, and 59 were 6 to 12 months of age. Mean weight was 6.5 kg +/- 1.7. Seventy patients received a transannular patch. The hospital mortality rate was 3% and there were no late deaths. Cumulative follow-up was 180 patient-years. Causes of death included hypoplastic pulmonary arteries (4 and 5 months old) and right ventricular failure (4 months old). The most important factors influencing right ventricular outflow tract reconstruction were neither weight (p = 0.90) nor age (p = 0.05) but rather were the ratio between weight and pulmonary arterial outflow tract diameter (p = 0.0005) and the ratio between body surface area and pulmonary arterial outflow tract diameter (p less than 0.0001). The last 48 patients were operated on with no deaths. During this period, operative management differed essentially in myocardial protection with blood cardioplegia. The predicted 30-day survivorship after repair was 90% to 99% (95% confidence limits). No ventricular arrhythmias have been detected after repair (mean follow-up 22.2 months). Mean right ventricular/left ventricular end-diastolic dimension ratio was (0.53 +/- 0.10 with M-mode echocardiography. These early results encourage us to proceed with primary repair of infants with symptomatic tetralogy of Fallot thanks to improved surgical management and enhanced myocardial protection.