The purpose of this study was to compare the effects of 2 mg/kg fluprazine (a serotonergic psychoactive drug with antiaggressive properties) on intrasexual attack, infanticide, and predation (on an insect larva) in males and females of wild and Swiss mice. The results showed that, in both stocks of mice, fluprazine significantly inhibited intrasexual and infanticidal attack in both sexes, but predatory attack was not altered by the drug treatment. Motivational and neural substrates underlying intrasexual attack and infanticide appear, thus, to be related to each other, and similarly modulated in both males and females. Conversely, predatory attack seems to be under a different neurohumoral control. The similar regulation of proximal mechanisms of aggressive behavior observed in wild and Swiss mice suggests a common neurobiology of aggression. For this reason, the outbred laboratory Swiss mice appear to be a reliable model for studies on causal and functional mechanisms of aggression.