Healthy men, aged 21-28, were divided into two groups according to the DSM-III diagnosis of alcoholism in their biological fathers. Evoked potentials from each subject were measured according to a visual odd-ball paradigm designed to elicit large responses in the midline parietal, Pz, lead. Subjects with alcoholic fathers produced significantly smaller amplitudes of the P3 component compared to subjects with non-alcoholic fathers. Reaction time, task difficulty and subject drinking history did not distinguish the groups. Subject's drinking history was not related to P3 amplitude.