Percutaneous transluminal balloon angioplasty of coarctation of the aorta was performed on eleven patients, aged 5-35 years (mean 25 years). Three patients had had surgical resection of the coarctation previously. There were no complications. The balloons used had a diameter up to 20 mm and were inflated with pressures of 3-5 bar for 10-60 sec. In two of the preoperated patients dilatation did not succeed. It was successful in the remaining nine. In these patients the gradient was reduced from a mean of 58 +/- 17 to 18 +/- 11 mm Hg, the stenosis diameter being increased from 4.5 +/- 2.4 to 11.9 +/- 5.1 mm. In five of six patients, angiography three or twelve months postoperatively demonstrated persisting dilatation. It is concluded that this procedure can be successfully used in both juveniles and adults, not only in children.