Eighteen patients with schizophrenia and 18 patients with affective disorders (depression) underwent regisTration of auditory event-related potentials (ERPs) recording in oddball paradigm. All the patients were in remission. In both groups of the patients, the N100 ERPs amplitudes to non-target stimuli were significantly smaller and N200 and P300 latencies were longer than in 18 normals. In the patient's group with affective disorders, prolongation of P200 and N100 ERPs latencies to target stimuli has been found. The group of patients with schizophrenia was characterized by P300 amplitude reduction. The results show stimuli processing decrease in patients with affective disorders, while in patients with schizophrenia a cognitive function disturbance was recorded.