Between January 1986 and October 1988, 11 young patients aged from 3 months to 29 years (10.6 years) underwent percutaneous transluminal angioplasty for recoarctation of the aorta. The procedure was performed 3 months to 21 years (6.7 years) after the initial operation for coarctation (9 cases: 8 terminoterminal sutures and 1 Waldhausen operation) or for complete interruption of the aortic arch (2 cases: direct terminoterminal suture with banding of the pulmonary artery in 1 case and closure of an aorto-pulmonary fistula in the other case). The diameter of the balloon selected was at most 1 to 1.5 mm wider than that of the smallest diameter of the aorta upstream or downstream of the stenosis, as measured by prior aortography. Adverse events recorded were thrombosis of the femoral artery in a 1-year old child, transient subendocardial lesion wave during dilatation in another child, and regressive left bundle branch block in a third patient. In one patient a small aneurysm developed at the site of dilatation: it was perfectly stable after 8 months. A satisfactory result was obtained in 4 cases, with a 52 to 95% increase in diameter of the stenosis and reduction of the gradient which fell from 56 mmHg on average to 18.25 mmHg. One child was lost sight of; in the remaining 3 patients the result remained stable after 6 to 20 months. A partial result (widening of the stenosis without change in gradient) was obtained in 2 cases. Five of the 11 cases were failures.(ABSTRACT TRUNCATED AT 250 WORDS)