Brainstem auditory evoked responses (BAERs) were recorded in 40 patients with clinically definite brainstem infarction, and results were compared to localizations from physical signs and CT scans. The BAER was abnormal in 92% of patients with evidence on physical examination of dysfunction of lateral structures in the pons or midbrain. Normal BAERs were seen with medially-situated or medullary lesions. When both rostrocaudal level and lateralization were considered, the BAER indicated damage in additional areas not evident on physical examination in 25% of patients. However, physical signs indicated damage in areas not reflected by the BAER in 22% of patients. Therefore, the BAER complements the localization obtained from physical findings. BAERs were abnormal in more of these patients than were CT scans, and thus are useful for confirmation of bedside impressions.