Ovarian physiology attracts an ongoing research effort that has revealed a complex network of regulatory mechanisms involving steroid hormones, gonadotropins, growth Factors and their cognate binding proteins, and, lastly, cytokines This chapter reviews the findings concerning the possible role for cytokines in ovarian physiology Because they are primarily active in inflammatory and inflammatory-like phenomena, cytokines were hypothesized to be involved in the ovulatory process, because the latter bears resemblance to inflammatory processes in several respects (1), The specific focus of this review is interleukin-l (IL-I), a prominent representative of this group of peptides, and one that has been extensively evaluated in the context of the ovary.