P300 auditory evoked potentials were recorded in 27 schizophrenic patients in the standard oddball paradigm. P300 amplitude in the right frontal zone correlated positively with the age of the patients at the onset of disease. As compared with normal (18 subjects), schizophrenics showed both smaller P300 amplitudes and longer latencies. The findings are assumed to reflect impairment of information processing in schizophrenia. It is emphasized that the level of impairment is higher when the disease occurs in adolescence.