A consecutive series of 118 patients operated on for ruptured intracranial arterial aneurysms was studied. Ninety-six of them could be adequately examined with a battery of psychological tests and computed tomographic scans 1 year after a subarachnoid hemorrhage. Seventeen orthopedic control patients with no history of brain damage were also tested. The pattern of cognitive deficits was strongly related to the findings on the computed tomographic scans. Patients with left lateral infarctions had deficits on performances requiring verbal efficiency, including memory and classification tasks, whereas patients who had right lateral infarctions were poor on a visuoconstructional task (the copying of Rey's Figure). These deficits were pronounced when lateral infarction was associated with diffuse brain damage. Patients with frontal medial infarctions had low scores on memory tests; the inefficiency in verbal fluency, categorical reasoning, and memory was related to diffuse brain damage. The patients who had no infarctions did not differ significantly from the control group. Cognitive impairments after left lateral and frontal medial infarctions, as well as diffuse brain damage, correlated with the Glasgow Outcome Scale.