The usefulness of CT and angiography for predicting the final ischemic brain damage resulting from supratentorial ischemic stroke was evaluated in 36 patients. CT was performed within 4 hr and angiography within 6 hr after the onset of symptoms. CT was used to assess the site and size of parenchymal brain damage and angiography was used to evaluate the cerebral circulation. A 3-month follow-up CT study was used to determine the site and size of final ischemic damage. Angiography was normal in six patients and showed complete occlusion in 30. Angiographic findings in patients with arterial occlusion were classified as either internal carotid artery occlusion or middle cerebral artery (MCA) occlusion. MCA occlusions were subdivided into occlusion before the origin of internal lenticulostriate arteries (type 1), occlusion beyond the origin of these branches (type 2), occlusion at the bifurcation of the main trunk (type 3), and occlusion of the peripheral branches (type 4). Collateral blood supply was also studied. Early CT findings were positive in 25 of 36 patients; the lentiform nucleus alone, the lentiform nucleus and the cortex, or only the cortex were involved. In all patients with positive early CT findings, angiography showed an arterial occlusion, often located in the main trunk of the MCA. Involvement of the lentiform nucleus on early CT was always seen in patients with internal carotid artery or type 1 MCA occlusion.(ABSTRACT TRUNCATED AT 250 WORDS)