The data relative to 13 years' experience with percutaneous transluminal renal angioplasty (PTRA) in the 13 major interventional radiology centers in Italy were collected and analyzed to evaluate technical and clinical results. Our aim was to collect homogeneous results in a large series of patients, evaluating both the technical and the clinical success with a long-term follow-up (1 month-13 years). One thousand three hundred forty seven PTRA procedures (including 42 restenoses) in 1,073 patients were retrospectively reviewed. In 807 cases the cause of stenosis was atherosclerosis, in 442 cases fibromuscular dysplasia and in 24 cases arteritis in 12 cases, stenoses were present in patients that had undergone a surgical by-pass. Sixty-two stenoses in patients with solitary kidney and 102 in patients with renal failure were studied separately. The technical success (based on the morphology of the dilated tract) obtained in 91% of cases was considered, together with the clinical success (in 81% of cases), based on the decrease in blood pressure evaluated according to Martin's classification. The blood pressure values collected after the maneuver were also evaluated separately for the different types of stenosis etiology: atherosclerosis, fibromuscular dysplasia or arteritis; moreover, blood pressure was studied in solitary kidney patients and in those with renal failure. Complications were classified as major (4.2%) and minor (4.9%). The high success rate and the low incidence of complications we observed in our series suggest PTRA as the procedure of choice for high blood pressure patients with renal artery stenosis > 50% of the normal caliber.