This contribution is a review of investigations on the role(s) of the anterior pituitary in chiropteran reproduction. Information on this subject has come mainly from histological studies of cytological changes during the annual cycle and mostly from hibernating temperate-zone species. Although direct evidence is unavailable, it appears that variations in the temporal synchronization of specific endocrine functions of the pars distalis are involved, at least in part, in several of the numerous reproductive specializations found in bats. Mention is also made of recent studies on the anterior pituitary of Macrotus californicus and its possible involvement in delayed development.