Maternal behavior was evaluated in 10 normal female mice and in 4 groups with brain lesions (neocortex, cingulate cortex, anterior thalamic nuclei, and septum). Ss with lesions in the septum were severely impaired in maternal behavior. Ss with other lesions were not markedly impaired. These findings contrast with earlier studies which showed that cingulate lesions in rats produced poor maternal care. The deficit was derived from disturbance of sequential organization of various behavioral acts involved in pup care and not from impaired motivation. It was suggested that lesion-disturbed maternal behavior arises from impaired inhibitory functions of the septum which normally prevent intrusion of out-of-order acts into the species-typical sequence of responses comprising maternal behavior. (PsycINFO Database Record (c) 2006 APA, all rights reserved)