The efferent connections of the septum in the pigeon were studied with the use of anterograde (3H-leucine autoradiography) and retrograde (horseradish peroxidase histochemistry) transport methods. It was observed that the dorsal septum projects to the lateral hypothalamus, portions of the periventricular hypothalamus, dorsomedial thalamus and midbrain reticular formation. Fibers from the ventral half of the septum (i.e., nucleus of the diagonal band) project to medial and lateral sectors of the hypothalamus, dorsomedial thalamus, lateral habenular nucleus and midbrain tegmentum. In addition, fibers originating from this region also project to the hippocampal and parahippocampal cortices.