Nonspecific aortoarteritis (NSAA) is a chronic disease of unknown etiology and may result in stenosing and obstructive lesions of the aorta. Transluminal balloon angioplasty was carried out in 17 children, 4-12 years of age (mean 8.9 +/- 2.7 years) with symptomatic stenosis of thoracic or abdominal aorta due to NSAA. Hypertension was present in 15 children, and 11 had significant left ventricular dysfunction. All children had a clinically inactive disease. The stenosis was in descending thoracic aorta in 10, thoracoabdominal in 3 and only abdominal in 4. Symptomatic improvement with relief of stenosis was seen in 16 of 17 children, although in 3, the results were suboptimal. The peak systolic gradient fell from 70.9 +/- 19.3 mmHg to 32.0 +/- 19.2 mmHg immediately after dilation (P < 0.0001). Angiographically measured luminal diameter stenosis also fell from 82.5 +/- 7.7% to 19.4 +/- 11.8% (P < 0.0001). Dissection flap was seen in 13 cases. It was large in cases with long, diffuse and eccentric stenosis of the thoracic or thoracoabdominal aorta. On follow-up (available for 14 of 16 cases for a period of 2-87 months mean 20.7 +/- 21.5 months, median 15.5 months) two patients developed restenosis. Left ventricular function improved in all 8 children that had sustained benefit of angioplasty. Blood pressure normalized in 9 of 13 children and the drug requirements fell in 4 others. Further remodeling of the lesion with decrease in gradients and luminal stenosis was observed in 11 children that have been restudied. Balloon angioplasty of aorta in children with NSAA is a feasible and safe procedure. Small intimal flap is seen in the majority, extensive dissection is more likely in the long diffuse lesions in descending thoracic aorta. Hypertension and left ventricular dysfunction improve after relief of obstruction.