In a preliminary study of 52 patients with cerebral vascular disease, clinical and electroencephalographic evaluations were compared. Most of the patients were in the sixth and seventh decade of life and had had symptoms of cerebral vascular disease for over a year. Seventeen of the patients had clinical evidence of intermittent cerebral ischemia. When routine electroencephalographic techniques were used, 47 per cent of the records were within normal limits. Twenty patients with cerebral vascular disease, eight of whom had clinical cerebral vascular insufficiency, were studied during posturally induced hypotension. No activation was detected in any of these 20 patients. It would appear that other methods of activation, including tilt-table studies, and serial recordings should be further explored and evaluated in these disorders if more clinically useful information is to be gained.