• Clozapine is a unique compound belonging to a relatively new group of antipsychotic agents, the dibenzazepines. To our knowledge, the present study represents the first double-blind, controlled comparison recorded in the United States. The data suggest that clozapine in the present population of newly admitted, acutely psychotic schizophrenic individuals, and in the doses employed, was more effective in overall improvement response, discharge rate, and ameliorating discrete symptoms across the different objective rating scales used than was chlorpromazine (Thorazine) hydrochloride. Placebo was ineffective. Unlike chlorpromazine, no extrapyramidal reactions occurred in those patients ingesting clozapine. Clozapine was also beneficial in reversing abnormal involuntary motor movements. It is an excellent anxiolytic and hypnotic agent. Sedation, hypotension, and hypersalivation are among the more common side effects observed.