A facial discrimination task adapted for use in an event-related potential paradigm was administered to 15 male subjects following oral administration of placebo and 0.56 g/kg alcohol. The stimuli (digital photographs of males and females with happy, sad and neutral facial expressions) generated a series of waves including a prominent positive potential with a latency between 400-550 msec, designated the P450. Three factor repeated measures multivariate analysis of variance was used to evaluate the effect of alcohol on the amplitudes and latencies of the P450 component to the happy and sad faces. As compared to placebo, following alcohol ingestion, male subjects had decreased P450 amplitudes but only to male happy faces compared to female happy faces. These data suggest that this ERP paradigm may be sensitive to detecting subtle effects of alcohol on brain responses to gender-related affective stimuli.