The involvement of the satiety-controlling hormone leptin in the modulation of the reward-associated dopamine release was investigated by monitoring the extracellular dopamine concentration in microdialysates from the nucleus accumbens of rats during feeding after infusion of leptin or artificial cerebrospinal fluid into the lateral ventricle of rats. Leptin suppressed the basal as well as the feeding-evoked extracellular dopamine concentration and reduced the amount and duration of food intake compared to the pair-feed vehicle-treated controls. These results suggest that leptin is involved in the dopaminergic modulation of feeding-induced rewarding functions.