Twenty chronic male schizophrenic subjects aged 30–50 years were examined by an auditory event-related potential procedure for the evaluation of the P300 component, a CT scan and a neuropsychological test battery. The P300 latency was increased and its amplitude was reduced. CT scan measures showed lateral and third ventricle enlargement, and there was a global neuropsychological impairment. Poor neuropsychological performances were consistently associated with delayed P300 latencies, but not with CT scan measures. Ventricular enlargement was more pronounced among subjects with a negative family history for major psychiatric disorders.