Absence of consensus persists regarding the optimal procedure and timing for the surgical treatment of young infants with symptomatic tetralogy of Fallot. From 1987 through 1992, 56 patients with tetralogy of Fallot were operated on at less than 6 months of age. Forty-one patients (median age 2.9 months) underwent primary repair and 15 (median age 2.4 months) underwent initial palliation. Mean follow-up was 24.2 +/- 16.4 months. No strict protocol was used but patients who received initial palliation were younger, had a smaller pulmonary arterial tree, or had anomalous coronary artery. Two patients died (overall mortality 3.6%; 95% confidence limits 0% to 11%), one after initial palliation (6.7%), and one after primary repair (2.4%) (P = 0.47). Eight of the 15 patients who received initial palliation underwent repair and had an increase in pulmonary anulus size at the time of definitive repair (mean difference Z-value = 2.2 +/- 1.6 standard deviation; p = 0.006). Transannular patch was required in 50% of patients who underwent repair (56% among patients having primary repair versus 13% for patients having initial palliation; P = 0.03). Five patients underwent reoperation. Early primary repair of symptomatic tetralogy of Fallot was achieved with a low mortality rate and is the preferred protocol. Initial palliation remains indicated in case of associated cardiac anomaly, very low weight, or severely hypoplastic pulmonary artery tree.