Carotid and vertebrobasilar transient ischemic attacks (TIAs) were clinically and angiographically correlated in 85 patients who had four-vessel angiography within 2 weeks after a TIA. The patients were divided into carotid and vertebrobasilar groups by clinical criteria. In the correlations of symptoms with arteriography, lesions of the contralateral internal carotid artery were observed in 54 percent of the patients. Of 39 patients with vertebrobasilar symptoms, 34 percent also had one carotid lesion and six patients had combinations of symptoms of both carotid and vertebrobasilar disease. In correlation with carotid bruits of the 85 patients, bruits were heard over one carotid artery in 42 percent. Subclavian bruits were heard in 47 percent of the patients with vertebrobasilar symptomatology. TIAs owing to arteriosclerosis of the cervical arteries occurred in 85 percent of the patients, but there was no significant difference in the incidence of atherosclerosis-induced TIA in the carotid and vertebrobasilar systems. For accurate population surveys of the prevalence of TIAs, and for clinical decisions, proper categorization of patients is necessary.