The purpose of the present study was to analyze the role of somatodendritic autoreceptors and postsynaptic 5-HT1A receptors in the modulation of maternal aggressive behavior. The 5-HT1A receptor agonist 8-OH-DPAT (8-hydroxy-2-(di-n-propylamino)tetralin) was microinjected (0.2, 0.5 and 2.0 microg/0.2 microl) in different brain areas of female Wistar rats: median raphe nucleus (MnR); medial septal area (MS); anterior corticomedial amygdaloid nucleus (ACoM); and dorsal periaqueductal gray (DPAG). The behaviors of lactating female rats with pups against a conspecific male intruder were recorded on day 7 post-partum. Results showed that in the median raphe nuclei, in the dorsal periaqueductal gray and in the corticomedial amygdaloid nucleus 8-OH-DPAT decreased maternal aggression; while in the medial septum, the intermediate dose (0.5 microg/0.2 microl) of the 5-HT1A receptor agonist increased the aggressive behavior of the lactating female rat. It is concluded that the main role of the 5-HT1A somatodendritic autoreceptors and the post-synaptic receptors of the brain areas studied is to decrease maternal aggression, however, at a specific dosage, 8-OH-DPAT acting on postsynaptic receptors of the medial septal area can increase aggressiveness.