The effects of three benzodiazepines on human aggressive behavior were examined in 44 medically healthy men. Volunteers were administered either placebo, 10 mg diazepam, 15 mg chlorazepate, or 50 mg oxazepam orally using double-blind procedures. Approximately 90 min after drug ingestion, participants were given the opportunity to administer electric shocks to an increasingly provocative fictitious opponent during a competitive reaction-time task. Aggression was defined as the level of shock the participant was willing to administer to the opponent. Results support the notion that diazepam (but not all benzodiazepines) can elicit aggressive behavior under controlled, laboratory conditions. Implications regarding the clinical use of various benzodiazepines for the tranquilization of potentially assaultive patients are discussed.