To assess the influence of surgical technique on the need for reoperation after coarctation repair in infancy, follow-up data were analyzed for 125 consecutive infants (less than 12 months) who underwent repair of coarctation of the aorta by subclavian angioplasty or resection and end to end anastomosis. Sixty-three infants underwent coarctation repair by resection between 1960 and 1980, and 62 underwent subclavian angioplasty between 1977 and 1985. The mean age (+/- SEM) at operation for infants with subclavian flap angioplasty was 1.54 +/- 0.93 months and for infants with resection was 2.70 +/- 0.93 months (p = 0.02). There was no difference between the groups in patient weight at initial repair or the proportion of patients with complex anatomy or aortic arch hypoplasia. Follow-up duration for the subclavian flap group was 2.55 +/- 0.51 years (range 0.3 to 8.2), and for the resection group was 7.97 +/- 3.61 years (range 0.6 to 21). Indication for reoperation was the presence of a coarctation gradient at rest of 40 mm Hg or greater and arm hypertension. Reoperation was required in 5 patients in the subclavian flap group and 12 patients in the resection group. The mean reoperation rate after subclavian flap repair was 0.0356 reoperations per patient-year, and after resection was 0.0342 reoperations per patient-year (p = 0.94). To determine an individual's risk of requiring reoperation from these group measures, a reoperation risk model was developed. The risk of reoperation by the fifth postoperative year was found to be 16.3% after subclavian flap repair and 15.7% after resection.(ABSTRACT TRUNCATED AT 250 WORDS)