Four patients who fulfilled all the clinical criteria for brain death, and 17 patients who did not, were tested with brainstem auditory evoked responses (BAER). Of the brain-dead patients, 3 had no waves present in the BAER, including wave. I. Initially BAER were intact in none of the brain-dead patients and then showed a decrease in amplitude and a prolongation of latency of the later components (7 cases) until finally wave I alone was present (6 cases). Normal data suggested toxic or metabolic comatose patients (2 cases). BAER are an objective measure of one of the sensory pathways traversing the brainstem and can be used to evaluate the functional states of the brainstem in patients in whom brain death must be considered. The association of short-latency somatosensory evoked responses (SER) has greater clinical utility in the brain death setting because it is important to have a wave present which establishes that the input signal has reached the central nervous system.