• In a longitudinal study of 119 patients with minor head injuries, 13 had abnormal auditory brain-stem responses (ABRs) within 48 hours after trauma. At follow-up examination one month later, ten patients had abnormal ABRs. The ABRs remained stable in most patients; in nine patients they normalized. However, in six patients initially normal ABRs became abnormal. This instability limits the medicolegal application of ABR testing after minor head injury.