The system comprised of Kit Ligand (KL) and its receptor c-Kit has proven to play a role in normal female reproduction and fertility in mammals. Gene expression studies have revealed that biological activities of ligands and receptors of the KL/c-Kit system are important in controlling apoptosis and cellular proliferation in reproductive tissues. Collectively, these studies have provided a better understanding of ovarian physiology and female fertility through the establishment of the concept that the KL/c-Kit system regulates the viability of primordial germ cells and follicles, initiation of primordial follicle growth, and further oocyte and follicular development through different signaling proteins. The purpose of this article is to review the importance of the KL/c-Kit system in ovarian follicular development, especially in the preantral phase of folliculogenesis