Unexpected and disappointing late results with the subclavian flap operation prompted this analysis of repair of coarctation in infants under 3 months of age. A total of 134 such patients underwent surgical repair since 1960 with 55 end-to-end anastomoses performed earlier in our experience (mean follow-up 5.0 years) and 67 subclavian flap angioplasty operations performed more recently (mean follow-up 2.0 years). The operative mortality was not significantly different (p = 0.3) between end-to-end anastomosis (29%) and subclavian flap angioplasty (19%), but it was significantly higher (p less than 0.01) in the first week of life (56%). Recurrent coarctation occurred in 16 cases, necessitating reoperation. The reoperation-free rates (with standard error) at 5 years for end-to-end anastomosis and subclavian flap angioplasty were 92% +/- 5% and 75% +/- 7%, respectively (p = 0.01). Eight of 10 patients who had reoperation after angioplasty had early recurrence with continued involution of the periductal tissues and growth of the posterior aortic ridge. Six patients who had recurrence after anastomosis demonstrated late anastomotic growth failure. The most common reoperation technique was patch aortoplasty (10 patients). The high incidence of early recurrence with subclavian flap angioplasty in infants under 3 months of age suggests end-to-end anastomosis as the procedure of choice when applicable.