Percutaneous transluminal angioplasty of the renal artery (PTRA) has been increasingly used over the past 20 years for treating renovascular hypertension (RVH). From the experience gathered so far it is justified to state that this technique is the first choice for patients with fibromuscular renal artery stenosis (RAS) because their cure rate is 50% and 42% improve. In contrast in patients with atherosclerotic RAS the cure rate after PTRA is 8-10% although 40-50% still improve. Since PTRA is associated with a 23% rate of major/minor complications and 30% restenosis (23% requiring stent implantation), it is obvious that in patients with atherosclerotic RAS the decision to attempt this procedure must be taken after careful selection of those who may actually benefit from the dilation. PTRA can be used more extensively for salvaging the function of the ischemic kidney than for treating hypertension because of the progressive nature of the atherosclerotic RAS and the lack of effective agents against such progression. After PTRA 35% of patients have some improvement in renal function and another 35% are stabilized. Yet most studies addressing the renal effects of PTRA suffer the limitation of having used serum creatinine levels as an indicator of glomerular filtration rate (GFR). More recent studies which used radioisotopic techniques to evaluate the changes of GFR induced by PTRA in the stenotic kidney indicate that after a successful procedure the increase is, on average, 8-10 ml/min. Interestingly it appears that this improvement is slower in kidneys of patients with atherosclerotic RAS than in those with fibromuscular RAS.