It is not rare for surgery of coarctation of the aorta to be complicated by recurrence of the lesion at medium-term, especially when it is performed very early in life. Advances in interventional catheterisation now offer an alternative to surgical reoperation. This study is a retrospective analysis of balloon angioplasty in 20 patients in whom isthmic stenosis had been operated before the age of one month in 19 cases, in whom recurrent coarctation was identified 3.2 +/- 2.1 months later. The percutaneous angioplasty was performed by a femoral arterial approach at an average age of 5.4 +/- 2.3 months. The femoral pulses returned together with a fall in the transisthmic systolic pressure gradient from 58.3 +/- 23.4 mmHg to 18.3 +/- 12.5 mmHg, and the isthmic lumen increased by +117 +/- 52%. Judged by the residual pressure gradient, the results were good, the best results being observed in the shortest and most severe stenoses. After a maximum follow-up of 5 years (average: 20.1 +/- 16.6 months), the angioplasty was successful in 14 cases (70%), 4 cases had a mild residual gradient (20%) and 2 were failures (10%). None of the patients required reoperation. There were no fatalities or early aneurysmal complications in the dilated zone monitored by echocardiography and magnetic resonance imaging. The only complication was femoral artery obstruction (6 cases) which was successfully thrombolysed in 5 cases but which recurred at long-term in 3 cases.(ABSTRACT TRUNCATED AT 250 WORDS)