We have previously demonstrated that intracerebroventricular injections of sulphated cholecystokinin octapeptide (sCCK-8) had a dramatic facilitatory effect on lordosis behavior in the gonadectomized, estrogen-primed male rat. In the female, sCCK-8 facilitates or inhibits lordosis when microinjected into the medial preoptic nucleus (MPN) or ventromedial nucleus of the hypothalamus (VMH), respectively. In order to identify sCCK-8 responsive sites that modulate lordosis behavior in gonadectomized males, sCCK-8 was microinjected into the MPN or VMH. Sulphated CCK-8 significantly increased lordosis behavior when microinjected into the MPN of estrogen-primed males, but had no significant effects when microinjected into the VMH. These results imply that CCK-sensitive neural substrates within the MPN may act to disinhibit lordosis in the gonadectomized, estrogen-primed male rat. The lack of an effect of VMH injection of sCCK-8 on lordosis in males is discussed in terms of possible sex differences in sCCK-8-sensitive lordosis-modulating circuits.