As an immediate early gene, c-fos plays a critical role in stimulating the synthesis and release of pituitary FSH via GnRH. To better understanding the mechanism how c-fos works in the transcription of FSHbeta under different frequency of pulsatile GnRH stimulation, this paper reviewed the signal trans- ductions initiated by c-fos in pituitary, which include cAMP pathway, MAPK pathway, Ca2+ /calmodulin-dependent kinases pathway and nuclear factor of activated T-cells (NFAT) pathway. It will be helpful for research in molecular targeted immunotherapy and eventually effective treatment to the infertility which resulted from defection or mutation of c-fos and c-fos related signal pathway elements.