Lactating rats were used in experiments to examine the role of the dopamine system in the regulation of ongoing maternal behavior. Administration of haloperidol disrupted retrieval behavior and nest building in a dose-dependent manner but not nursing behavior and pup licking. Feeding behavior including carrying of food pellets to the nest and general locomotor ability were not disrupted by haloperidol. Apomorphine effectively reversed the inhibition caused by dopaminergic blockade. These results indicate a role for dopamine in the motivational regulation of retrieval and nest building during the postpartum phase of maternal behavior.