A retrospective chart review was conducted of 20 older patients treated with clozapine, who were hospitalized for treatment of severe behavioral disruption secondary to psychotic symptoms. The average daily dose of clozapine was 208 mg for an average of 22 hospital days. Follow-up was 12 months after hospital discharge. All patients had significant behavioral improvement; there was modest reduction in psychotic symptoms (hallucinations and delusions). Clozapine was discontinued in two patients who developed respiratory symptoms. One patient developed seizures. Three of 18 patients developed leukopenia during the posthospital period, two at 6 weeks after beginning clozapine and one within 10 weeks. Clozapine was then discontinued and white blood cell count returned to normal. These retrospective observations suggest that clozapine is possibly useful in controlling behavioral disruption in older patients. Older patients may be at greater risk for developing leukopenia because of their higher blood levels of clozapine and possibly norclozapine.