Rats trained on an avoidance-escape task were administered buspirone in doses ranging from 0.5 to 7.5 mg/kg. Low doses disrupted avoidance responding without impairing escape responding. Rats trained on an experimentally induced conflict procedure were also administered buspirone or diazepam (1.0 to 5.0 mg/kg). Buspirone and diazepam appeared to be equipotent as anxiolytics. Cynomolgus monkeys, also trained on the experimentally induced conflict task, were given intramuscular buspirone or diazepam (0.5 to 5.0 mg/kg). Both drugs produced an attentuation of conflict, further supporting the anxiolytic equipotency of buspirone and diazepam. The long duration of action of buspirone suggests the presence of at least one active metabolite.