Brainstem auditory evoked responses (BAERs) were measured in pediatric patients with neurologic diseases. Abnormalities of interwave intervals, amplitude ratios, and response to changing rate of stimulation were found in patients with tumors, myelin disorders, anoxic-ischemic encephalopathy, trauma, and neurodegenerative disorders. Reversibility of brainstem abnormalities (excluding multiple sclerosis) and sensitivity to toxic-metabolic disorders are features of the response not previously described in adults with neurologic disorders. The BAER is a promising new tool for the investigation of pediatric neurologic disease.