Clozapine was used to treat nine brain-injured patients with psychotic symptoms or outbursts of rage and aggression refractory to other medications. Verbal and physical aggression decreased markedly in two patients, and one additional patient had a dramatic decrease in bizarre behaviors. Mild improvement occurred in three patients with a decrease in agitation and frequency of auditory hallucinations. Response was indeterminate in three patients because of inadequate length of treatment. The incidence of side effects appeared to be higher than expected, with seizures occurring in two of nine patients. These case reports illustrate that clozapine may be useful in the treatment of psychosis and aggressive behavior after brain injury, despite the occurrence of adverse effects.