Percutaneous transluminal dilatation was performed in 5 patients with unilateral atherosclerotic renovascular disease and one patient with occlusion of a renal artery. Hemodynamic activity of the stenosis was documented by determination of pre- and poststenotic blood pressure values and by measurement of renal plasma flow. Flowing transluminal dilatation all patients showed a significant drop in blood pressure and antihypertensive treatment could be reduced or even discontinued. Only one patient became hypertensive again 3 months after the dilatation procedure. In this patient both the reduction of renal plasma flow and the delayed nephrographic effect on the stenotic side in the intravenous urogram were interpreted as symptoms of a recurrence of significant renal artery stenosis. In 2 of the six patients with impaired kidney function glomerula filtration are increased, as documented by a decrease in serum creatinine values. The results show that percutaneous transluminal dilatation may be a valuable method in the management of renovascular hypertension.