Comparing studies on regional cerebral blood flow and circulation time were performed in 150 patients with cerebral disorders caused by stenosing disease of extracranial and intracranial arterial vessels and by ischemic attacks without angiographic visible disturbances of the cerebral arteries. Both radiological investigation of brain circulation by rapid serial angiography of carotid artery and rCBF measurements were performed under general anaesthesia with adequate steady-state conditions. Regional cerebral blood flow was studied by the 133Xe intraarterial injection method, employing a new 8-detector-equipment, manufactured by SIEMENS. In contrary to the traditional instrumentations the special constructions of the detectors and collimator blocks permit simultaneous measurement of rCBF in 8 areas without any overlapping of the counting areas and with high depth effect. The connection of rCBF-measurement with cerebral arteriography guarantess furthermore an exact attachment of rCBF values to defined regions of arterial blood supply, visualized on the x-ray film of the lateral angiogram. The correlation of CBF-abnormalities (ischemic foci, hyperaemic regions, focal vasoparalysis, globally depressed flow values and impairment of autoregulation) with neuroradiological findings are demonstrated and discussed.