Based on preliminary data suggesting that polydrug abuser subjects may have delayed wave V BAER latencies, we contrasted BAER latency and amplitude measures between a group of polydrug users and six different comparison groups of subjects drawn from our laboratory files. A series of analyses showed that BAER latencies were, in fact, prolonged for psychiatric polydrug users as compared with groups of medically screened and unscreened normals not using drugs and normals using marijuana only. However, further analyses which compared polydrug abusers with nondrug users or marijuana-only users drawn from a psychiatric patient population failed to confirm these differences, thus suggesting that psychiatric status was more important than polydrug abuse in producing BAER alterations. Furthermore, subsidiary analyses using wave I latency as statistical covariate suggested that wave V latency prolongations could, under certain circumstances, be epiphenomena or reflections of earlier wave I alterations.