Eight cases of presumed acute occlusion of intracranial arteries, 7 middle cerebral and 1 posterior cerebral, demonstrated the occluded artery as an abnormal high density structure on non-enhanced computed tomography. Three cases underwent subsequent angiography which confirmed the diagnosis. CT scanning is therefore able to visualize acute thromboembolism in the intracranial arteries. In the appropriate clinical setting of acute stroke, an artery visualized on non-contrast CT scan as diffuse high density and higher in density than other visualized vessels should be suspected as acutely occluded by clot.