The action of diazepam (0.0, 1.0, and 2.0 mg/kg) and the serotonergic compounds buspirone (0.0, 2.5, and 5.0 mg/kg) and 8-OH-DPAT (0.0, 0.1, and 1.0 mg/kg) on maternal behavior and aggression were studied. An activity test was made after these treatments to control for unspecific actions due to motor impairment. Diazepam and buspirone dose-dependently inhibited the expression of maternal aggression and the active components of maternal behavior such as retrieving and nest building. 8-OH-DPAT did not affect these behaviors. 8-OH-DPAT (1.0 mg/kg) provoked the serotonergic syndrome and hypothermia; however, ovariectomized animals showed more signs of the syndrome and a decrease in body temperature after 8-OH-DPAT than lactating rats. Buspirone, but not the other anxiolytics, reduced motor activity. The role of drugs acting at the serotonergic, dopaminergic, and GABA-benzodiazepine systems in the control of maternal behavior and aggression is discussed.