From July 1987 to December 1992, 52 patients underwent balloon-angioplasty of aortic coarctation at three units of pediatric cardiology in Austria (Graz = 35 patients, Innsbruck = 15 patients, and Vienna = 2 patients). 35 patients had postoperative and 17 had native coarctation. Mean age at intervention was 7 10/12 years with 2 patients under 1 year and 5 patients over 18 years old. The mean relation balloon diameter-coarctation diameter was 2.6 +/- 0.9. The blood pressure gradient between upper and lower extremities decreased from a mean of 44 +/- 16 mm Hg to 15 +/- 13 mm Hg (p < 0.0001). The diameter of the stenosed segment was increased from 5 +/- 3 mm to 8.5 +/- 3.5 mm (p < 0.0001). Native coarctation showed a significantly better result in respect to decrease of the gradient (36 +/- 12 mm Hg) than did postoperative coarctations (25 +/- 19 mm Hg) (p < 0.03). 13 patients did not respond adequately to angioplasty. 10 patients out of this group had tubular narrowings and belonged to the group of postoperative coarctations, whereas localized stenoses in native coarctations gave the best results. Localized wall irregularities were found in 4 patients with native coarctation. Balloon angioplasty of postoperative and native coarctations in childhood and adolescence is a secure and effective means of treatment and should be considered as therapy of first choice. The best results can be found in the group of the circumscript type of stenoses in native coarctation, whereas long and tubular stenoses in the group of postoperative coarctations give less satisfying results.