In this overview on the role of PAF in reproductive biology, we have emphasized its relationship to fetal lung maturation and the initiation and maintenance of parturition. In addition, we have discussed the role of this autacoid in certain complications of premature delivery. It should be pointed out, however, that it is our view that other mediators and cytokines also play a role in these processes. In the past, many investigators have suggested a central role for one of these mediators that serves as the "trigger" of these biologic events. It is our view that these systems are regulated by a number of effectors, among which PAF may play an important role.