Thirteen patients with severe, unilateral, atherosclerotic renovascular hypertension were treated with percutaneous transluminal renal angioplasty. The procedure produced wide patency of the stenosed vessel in 10 patients and partial dilatation in the remaining three. All patients exhibited a beneficial response in their hypertension; at latest follow-up, ranging from two to eighteen months, all patients were normotensive, four in the complete absence of any antihypertensive medication and the remaining nine while taking substantially less medication than before. Suppression of the differential renal-vein renin ratio was also documented. In one patient follow-up angiography, performed after seven months because of deterioration in renal function, revealed an occluded renal artery. Complications that were encountered included two small, segmental renal infarcts, three episodes of nonoliguric, presumably radiocontrast-induced, acute renal insufficiency and a soft-tissue hematoma that occurred one month after the procedure and was due to excessive anticoagulation. Percutaneous transluminal renal angioplasty may be an effective modality in the management of unilateral, atherosclerotic renovascular hypertension.