Despite gratifying immediate results, significant recoarctation at follow-up has been observed after balloon angioplasty of native aortic coarctation. Risk factors for such recurrences have been identified in one of our previous studies. In this study we examined the value of these risk factors in the prediction of recoarctation after balloon angioplasty. During a 6-year period ending in September 1993, 37 infants and children aged 2 days to 15 years underwent balloon angioplasty of native coarctation with resultant reduction in coarctation gradient from 45 +/- 17 (mean +/- SD) to 12 +/- 9 mm Hg (p < 0.001). On the basis of results of 4- to 48-month follow-up catheterization in 30 children, recoarctation developed in 8 (27%) children. The data from these patients were scrutinized to identify subjects that exhibited the previously determined risk factors, namely age < 12 months, size of aortic isthmus less than two thirds the size of the ascending aorta, coarcted aortic segment < 3.5 mm before angioplasty, and coarcted segment < 6.0 mm after angioplasty. Then, thirty variables (Table I) were examined by logistic regression to identify factors responsible for recoarctation; the data from both study groups were combined for this analysis. The prevalence of recoarctation in each subgroup with a given number of risk factors is similar (p < 0.1) to that observed in the initial study identifying the risk factors. In addition, logistic regression identified age (p = 0.014), size of isthmus (p = 0.006), preangioplasty coarcted segment (p = 0.01), and postangioplasty coarcted segment (p = 0.006) as risk factors.(ABSTRACT TRUNCATED AT 250 WORDS)