Brainstem auditory evoked responses(BAERs) were studied in thirty six patients with clinically definite vertebral-basilar transient ischemic attack(TIA). BAEP tests were performed relatively immediately after the ictus (48 hours) of vertebral-basilar TIA in twenty-three inpatients and in seven to fourteen days in thirteen outpatients. Among thirty six patients with vertebral-basilar TIA, abnormal BAER findings were detected in fourteen (38.8%). The abnormal BAEP findings were bilateral in eight (57.2%) and unilateral in six (42.8%). The BAER abnormalities revealed the prolongation of I-III interpeak latencies in eight (57.2%), of III-V interpeak latencies in three (21.4%), and of only I-V interpeak latencies in three (29.4%). The incidence of abnormal BAER findings were much more frequent in patients on whom the tests were studied relatively immediately after the ictus than in the others. The serial BAEP studied in one patient showed mild decrease of prolonged I-V interpeak latencies. Therefore it is concluded hat brainstem auditory evoked responses could be helpful in patients with vertebral-basilar TIA as a diagnostic test to complement the physical examination and differentiate from other diseases of similar symptomatology.