Late components of brain event-related potentials reflect aspects of selective attention, stimulus evaluation, and possibly memory update mechanisms. Several of these components were measured during an auditory target detection task, performed by 20 schizophrenic and 20 normal subjects. Both the amplitude of those components and a more general late amplitude measure were significantly reduced in schizophrenics, for both target and non-target stimuli. One general late amplitude measure, from the scalp vertex, could alone correctly classify 85% of patients and 95% of controls. The source of these differences may lie in a protracted positive potential shift.