Objective: The authors examined the efficacy of intramuscular flunitrazepam compared with intramuscular haloperidol for the immediate control of agitated or aggressive behavior in acutely psychotic patients. Method: Twenty-eight actively psychotic inpatients, aged 2060 years, who were under treatment with neuroleptic agents were selected for the study. Each was randomly assigned on a double-blind basis to receive either 5 mg i.m. of haloperidol (N=13) or 1 mg i.m. of flunitrazepam (N=15) during an aggressive event. Verbal and physical aggression was measured over time with the Overt Aggression Scale. Patients were also rated with the Brief Psychiatric Rating Scale and the Clinical Global Impression scale. Results: Both flunitrazepam and haloperidol exhibited acute antiaggressive activity. This beneficial effect, as assessed by the Overt Aggression Scale, was obtained within 30 minutes. Conclusions: Intramuscular flunitrazepam may serve as a convenient, rapid, safe, and effective adjunct to neuroleptics in reducing aggressive behavior in emergency psychiatric settings.