Relationship between forebrain lordosis inhibiting system and serotonergic mechanism was examined in estradiol benzoate (EB) and progesterone (P)-primed ovariectomized rats. In order to remove the forebrain inhibition of lordosis response, anterior roof deafferentation (ARD) which interrupts the dorsal inputs to the POA coming down anterior to the anterior commissure or medial preoptic area lesions (POA-L) were made. All experimental females pretreated with EB and P showed high levels of lordotic activity. Soon after the behavioral tests, the animals were injected with 10 mg/kg p-chloroamphetamine (PCA) intraperitoneally and tested again 30 min later. PCA strongly suppressed female sexual behavior. Regardless of the presence of ARD or POA-L, no PCA injected females showed lordosis. From these results, it can be said that serotonin may not directly act on the forebrain lordosis inhibiting system.