Inhibin B is a hormone which may be used in the evaluation for testicular function. Inhibin B is a hormone secreted by the Sertoli cells. It has been shown that lower levels of Inhibin B and even loss of levels of Inhibin B occur in men after chemotherapy or radiation therapy. Others have suggested that using reference values for Inhibin B and Inhibin B to FSH ratio are more sensitive markers of male infertility than FSH alone . Even so, Inhibin B as a direct marker determining spermatogenesis has shown conflicting results in the literature, and does not seem to predict sperm presence in azoospermic patients. Because of the conflicting results in the literature, the potential role of serum Inhibin B as a marker for predicting spermatogenesis is not routinely used.