Oxazepam (2.5-80 mg/kg) induced significant mouse killing among large samples (N = 100/dose) of Holtzman strain albino rats. Meprobamate (2.5-80 mg/kg) and Chlorpromazine (0.5-4 mg/kg) did not induce killing. Despite its lesser tendency to induce aggression in humans, Oxazepam is as potent as Chlordiazepoxide for inducing killing by rats. Induction of mouse killing by rats appears to the predict clinical potency rather than the aggressive side-effects of anxiolytic benzodiazepines.