Event-related potentials (ERPs) elicited during information processing tasks are useful for assessing brain function. Abstinent male alcoholics exhibit deficits in ERPs. The present study found that female alcoholics with early onset alcoholism (18.3 +/- 1.3 years) showed significant deficits in P300 amplitude relative to both high-risk and low-risk controls. Two interpretations of these findings are possible. P300 amplitude reduction among the alcoholic women might be a neuropathological consequence of excessive drinking. Alternatively, lower amplitude of the P300 wave may be a marker for alcoholism risk segregating within high-risk families and associated with development of alcoholism. The later interpretation is favored based on the unlikely possibility that the nonalcoholic high-risk women would later convert to alcoholic status due to their age (mean age of 35.6 +/- 1.6 years).