A correlation study of CT and angiography was done in 100 patients who had clinical evidence of cerebrovascular occlusive diseases. 4-vessel cerebral angiography was done in all patients except 4 cases, and clinical findings including the time of onset and etiology of vascular occlousion were not included in the evaluation. 81 patients had positive CT findings, and the lesions were most frequently found at middle cerebralartery (MCA) territory(40%). On angiography, 63 patients had vascular occlusive lesions including 5 cases of venous thrombosis. MCA was the most frequent site of arterial involvement (57%), and followed by internal and/orcommon carotid(47%) and vertebro-basilar-artery(12%). Poor correlation was obtained between CT and angiographic findings (Good 30%, Fair 36%), and the lesions in branches made more positive result on CT(83%) than internaland/or common carotid lesions (54%). The degree of stenosis or time interval between CT and angiography had norole in the correlation. But good collateral circulation demonstrated on angiography significantly contributed to the negativity of CT finding.