Percutaneous transluminal renal angioplasty was performed in 54 consecutive patients with hypertension and renal artery stenosis caused by Takayasu's arteritis. Angioplasty was technically successful in 67 (89.3%) of 75 lesions attempted. In these 67 lesions, the degree of stenosis decreased from 88.3 +/- 4.8% to 23.5% +/- 13.6% (p < 0.001) after angioplasty. Following successful angioplasty there was significant improvement in hypertension (p < 0.001) within 48 hours. Patients with bilateral renal artery stenosis had higher systolic blood pressure both before balloon dilatation (p < 0.05) and after balloon dilatation before discharge (p < 0.001), compared with patients with unilateral renal artery stenosis. Three to 70 months (mean 26.4 +/- 10.3 months) after successful angioplasty, blood pressure was reduced to normal or was improved in 93% of patients. Angiographic restudy an average of 14.2 +/- 7.8 months after angioplasty showed restenosis at the same site in 7 of 52 (13.5%) lesions and fresh stenosis in one artery. All these eight lesions were successfully dilated. Further improvement in the luminal diameter was observed in 11 (21.2%) lesions. Late angiographic restudy in seven patients an average of 56.1 +/- 6.3 months after angioplasty showed no restenosis. Our results suggest that balloon angioplasty is safe and highly effective in relieving renal artery stenosis caused by Takayasu's arteritis and should be the treatment of choice for renovascular hypertension in this disease.