Scalp-recorded event-related potentials (ERPs) are sensitive indicators of subtle alterations in cerebral processes. We assessed automatic auditory adaptation and detection of novel stimuli in violent and non-violent alcoholics and normal subjects. Source analysis of ERPs revealed active medial temporal and frontal regions in all subjects. Frontal lobe processed alerting tones in violent alcoholics, whereas non-violent alcoholics and normal subjects processed them in medial temporal brain areas. Detection of deviant tones appeared simultaneously in frontal and temporal areas in violent alcoholics, but sequentially in other groups. These findings imply alterations in arousal and involuntary adaptive processes in cortical networks associated with violent behaviour and alcoholism.