A total of 33 patients with a relevant stenosis or occlusion of extracranial arteries were tested for a number of neuropsychological functions. Most of them [22] suffered from transient ischemic attacks, 6 from strokes, 5 were asymptomatic. Compared to an age-matched population of normals, patients showed an impairment in their mnemic functions, and attention under stress as well as in their psychomotor function. The degree of neuropsychological impairment was independent of the unilaterality or bilaterality of carotid stenoses. The results illustrate the neuropsychological deficit even in asymptomatic patients and those with complete recovery from transient neurological deficits.