The following studies evaluated whether direct placement of estradiol into different brain areas could increase the satiating potency of CCK in female rats. In Experiment 1, estradiol implants in the PVN, but not in the VMN or third ventricle, significantly enhanced the satiety actions of CCK (5.0 micrograms/kg). In Experiment 2, a lower dose of CCK (0.5 micrograms/kg) suppressed food intake in females with estradiol implants in the PVN but not in animals with implants in the VMN or preoptic area. In both experiments, estradiol implants in the PVN significantly lowered food intake and body weight during the 2-day period of hormone treatment. Implants in other areas had no significant effects on feeding or body weight. These data support the hypothesis that the satiety effect of CCK is enhanced by estradiol and suggest that the PVN is involved in the interaction between CCK and estradiol.