Auditory brainstem evoked response-(ABR) may be affected by changes in cerebral blood flow. Apart from its primary indications for prevention of stroke and transient ischemic attacks - (TIA's), internal carotid endarterectomy - (ICE) has been shown to improve cognitive function and cause diminution of tinnitus and vertigo. A one-week postoperative ABR previous study of patients undergoing ICE demonstrated no change in ABR recordings. In order to evaluate possible late changes, we have conducted a prospective study of the delayed effects of ICE on ABR in 13 patients. No initial pathology was noted and no significant change found in any of the absolute and interpeak latencies of ABR waves.