The relationship between symptoms of schizophrenia and abnormalities in the P300 component of the event-related potential (ERP) was investigated in 22 and 27 patients diagnosed with positive and negative profile schizophrenia, respectively. The Positive and Negative Syndrome Scale (PANSS) was used to characterize clinical symptoms. A group of 30 normal controls were also studied. Results showed that patients with schizophrenia exhibited reduced P300 amplitudes compared with controls and that those with negative profile schizophrenia had amplitude decrements and longer latencies. These findings suggest that there are neurobiological differences between positive and negative profile schizophrenia.