Catheter-dilatation (percutaneous Transluminal Angioplasty=PTA) of renal artery stenoses can be applied successfully and without major risk even in patients with high operative risks. Therefore, the indication for the diagnostic evaluation of renal artery stenosis should be expanded to all patients suspected to have renovascular hypertension. Excretory urography combined with angiotomography offers the possibility to visualize the renal arteries and to either detect or exclude arterial stenosis. In the first part results of this procedure are presented. The bolus injection have been carried out on 415 patients without any serious side-effects. Using angiotomography 49 renal artery stenoses, 1 aneurysm and 1 AV fistula could be detected. Catheter-angiograms, angiotomograms and conventional rapid sequence urograms were compared in 91 patients. For angiotomography a sensitivity for the presence of renal artery stenosis of 93% and a specifity for the absence of arterial stenosis of 99% can be attained. In the second part, the results of PTA of renal artery stenoses in 35 patients are described. PTA was technically successful in 29 patients (83%). Three clinically silent complications are reported. In a mean follow-up period of 8,2-months, hypertension was normalized in 13 (45%) and improved in 10 (34%) patients. Renal insufficiency could be normalized in 7 out of 11 patients. These results make PTA the method of choice in treating renovascular hypertension. Only if this method is not applicable or technically not feasible, is the alternative for treatment surgical revascularization or conservative antihypertensive therapy.