A new method to demonstrate the renal arteries is presented. It consists of taking with a Synchroplan apparatus simultaneous tomographic sections during the aortic and arterial stage of intravenous urography (IVU). Direct visualization of the vessels avoids the false negative results of IVU alone in investigations of renovascular lesions, such as bilateral stenosis of the renal artery, stenoses with few functional disorders, aneurysms and associated arterial and urinary lesions. Lesions of the infra-renal portion of the aorta and of the splanchnic arteries are also visualized. In a series of 37 patients investigated for renovascular hypertension, the new method proved more sensitive, more specific and of higher predictive value than conventional IVU. In another series of 19 patients who had undergone revascularization of the kidneys, the authors were able to obtain good visualization of the new vascular system and to establish correlations between morphological features and the effects of hypertension. The method therefore appears to be valuable in detecting renovascular lesions in arterial hypertension, monitoring renal artery lesions and following up patients with surgical revascularization.