Significant central nervous system toxicity in frontal brain regions has been demonstrated with chronic alcohol consumption both on autopsy and using neuropsychological testing. This study examined the latency of an objective and reproducible brain event-related potential measure of frontal cortex function in chronic elderly male alcoholics who were abstinent 3 months-2 years, a patient group in whom the central nervous system effects of chronic alcohol abuse are thought to be largest and most persistent. We examined the latency of the P3A event-related potential component, which reflects a frontal maximum orienting response to novel stimuli. Twelve elderly abstinent chronic alcoholic males and 11 elderly male controls were studied in an auditory and a visual paradigm, each of which included target, nontarget, and novel rare nontarget conditions. In both modalities, the P3A response to the novel rare nontarget stimuli was significantly delayed in the chronic alcoholics. P3B delays to the target stimuli were also present in the alcoholics, with the P3A and P3B effects being independent of each other. For both P3A and P3B, the effects were larger and more consistent in the visual compared with the auditory modality. Our conclusions are as follows: (1) both P3A and P3B latency delays are evident in elderly abstinent chronic alcoholics; (2) separate mechanisms are responsible for these effects; (3) these effects are more sensitively detected in the visual versus the auditory modality; and (4) delayed P3A latency may be an objective and reproducible index of the frontal cortex effects of chronic alcohol abuse.