The optimum surgical procedure for treatment of coarctation of the aorta in the neonatal period remains controversial. To assess immediate and long-term results of using primarily the subclavian flap angioplasty procedure (SFA), we reviewed our initial 5-year experience. The average follow-up was 6 years. From 1977 to 1981, 25 infants under 3 months of age (1 to 86 days, mean 21) required emergency surgery for repair of coarctation of the aorta. Three groups of patients were identified. Group I consisted of 10 patients with or without patent ductus arteriosus. In group II, 10 patients had coarctation association with one or multiple ventricular septal defects (VSDs) without other congenital defects. In group III, 5 patients had coarctation associated with more complex congenital heart lesions. Twenty-three SFAs and two patch aortoplasties were performed. No patient with isolated VSD was banded. All patients except one in group III with an associated atrioventricular canal survived initial hospitalizations. Four late deaths occurred, all in patients with associated complex heart defects. There were three recurrent coarctations requiring surgery or balloon angioplasty (12%)--one in each group, with a total rate of 0.77 recurrences per 100 patient-months. SFA for coarctation in the neonatal period is a safe and effective operation with a low initial mortality (4%, 0-19%, 70% confidence limits) well tolerated in this group of ill patients. Long-term outcome is primarily related to the presence of associated complex congenital defects. Infants with VSD associated with coarctation did not require pulmonary artery banding unless primary intracardiac repair was not feasible.(ABSTRACT TRUNCATED AT 250 WORDS)