Plasminogen activator(PA) and plasminogen activator inhibitor(PAI) are involved in many physiological or pathological events. The Sertoli cells, the important elements within the seminiferous epithelium, are thought to play a key role in spermatogenesis. The Sertoli cells secrete PA and PAI. The levels of them are modulated by hormonal and cell-mediated influences. They play a fundamental role in the maintenance of spermatogenesis, sperm motility and fertilization.