The literature dealing with electrophysiologic research in alcoholics and individuals at risk for alcoholism is reviewed. Event-related potential (ERP) differences between family history positive (FHP) and family history negative (FHN) males have been reported both prior to the ingestion of alcohol and following alcohol challenge doses. At present, the most robust of these electrophysiological findings is the lower P3 amplitude of the ERP, which has now been replicated in several laboratories. This perhaps provides a phenotypic marker, distinguishing those at risk for alcoholism.