We attempted percutaneous transluminal renal angioplasty in 89 patients with hypertension and renal-artery stenosis (including 51 with atheromatous and 31 with fibromuscular stenoses) who were then followed for an average of 16 months (range, 4 to 40). Angioplasty was technically successful in 87 per cent of the fibromuscular stenoses and in 57 per cent of the unilateral atheromatous stenoses but in only 10 per cent of the bilateral atheromatous stenoses. After successful angioplasty, blood pressure was reduced to normal or improved in 93 per cent of the patients with fibromuscular dysplasia and in 84 per cent of the patients with atheromatous disease. Angiographic follow-up at an average of 21.8 months in 15 patients showed persistent relief of the stenoses and a 12 per cent average increase in kidney size. Renal angioplasty is effective for long-term control of hypertension in patients with renal-artery stenosis due to fibromuscular dysplasia or unilateral non-ostial atheroma.