Severe renal artery stenosis may cause renovascular hypertension; in case of bilateral narrowing or in a stenotic solitary or transplant kidney, renal insufficiency (ischemic renal disease) or rarely pulmonary flash edema may occur. In most cases arteriosclerotic disease is the underlying cause; less prevalent are the various manifestations of fibromuscular disease. Renal artery stenosis may be treated by revasularization, using either percutaneous (balloon angioplasty, stenting) or rarely open surgical procedures, both with excellent primary patency rates. However, randomized trials of renal artery angioplasty or stenting in patients with arteriosclerotic lesions have failed to demonstrate a longer-term benefit with regard to hypertension control and renal dysfunction over medical management alone. Careful patient selection is essential to maximize the potential benefit (e.g., in patients with refractory hypertension, progressive renal failure or recurrent pulmonary flash edema).