Intracranial administration of progesterone or a serotonergic receptor blocker into either the dorsal hippocampus or corticomedial amygdala, but not the septum, activated lordotic behavior in estrogen-primed female rats. The same intra-amygdaloid sites mediated the effects of both treatments, whereas in the hippocampus the regio superior was responsive to serotonergic receptor blockade and the dentate gyrus was responsive to progesterone. This is the first demonstration that the amygdala and hippocampus participate both in the facilitation of lordosis by progesterone and in a serotonergic system which inhibits female sexual behavior.