In 22 patients the regional cerebral blood flow (rCBF) was measured after intra-arterial injection of xenon 133Xe. In all patients cerebral angiography was performed after that and in 4 patients aortic arch angiography was done as well. In 2 cases of subclavian artery stenosis with normal state of the branches of the internal carotid artery the rCBF was not decreased. On the other hand, a significant decrease of rCBF was found in cases of transient cerebral ischaemic episodes with angiographically demonstrated bilateral stenosis of the afferent arteries and coexistence of stenosis of the afrerent arteries supplying the brain and intracranial arteries. On the basis of an analysis of rCBF angiograms the authors suggest the conclusion that a joint evaluation of the clinical manifestations, results of rCBF measurements and angiograms increases the accuracy of assessment of the condition of the cerebral circulation in patients qualified for patency-restoring operations.