Angioplasty of renal artery stenosis has been used extensively in the last two decades for treating renovascular hypertension, and, more recently, for preserving the jeopardized renal function. A large body of evidence has accumulated indicating that this approach is by far the most convenient for patients with fibromuscular stenosis, in whom the technical success of the procedure is followed by a high cure rate (50%) or at least by some improvement of blood pressure (40%). In contrast, in patients with atheromatous stenosis, the rate of cure is very low (8–10% at best) and the rate of improvement is between 40 and 50% irrespective of whether the stenosis is treated with angioplasty or with stent implantation. Thus, before undergoing procedures which are not devoid of potentially serious side-effects, these patients should be thoroughly investigated to select those in whom the benefit actually outweighs the risks. Studies investigating the effects of angioplasty on renal function are less numerous than those addressing the effects on blood pressure, and, in most cases, suffer the limitation of using the levels of serum creatinine as the sole marker of the changes in glomerular filtration rate induced by the procedure. These investigations have shown that some amelioration can be achieved in one-third of patients, with another third having unmodified levels of creatinine at follow-up. Radioisotopic techniques, which allow a more precise and separate evaluation of the function of the two kidneys, appear to be a promising alternative for the investigation of the effects of angioplasty; indeed, preliminary studies which took advantage of these methodologies have shown that the function of the stenotic kidney can possibly be rescued by slowly reversing the multiple mechanisms by which chronic ischaemia damages the kidney.