Abstract: Inhibin B is one of glycoprotein hormones secreted by testis and regulated specifically by follicle stimulating hormone from pituitary. Its secretion has circadian rhythm and it changes with aging. Inhibin B in male adult almost derives from testis and its assemble process is mostly finished in the spermatogenic cells. Then it is released to the circulation and seminal plasma. As a result， the levels of inhibin B in the serum and seminal plasma are synchronized to spermatogenesis. Enzyme linked immunosorbent assay （Double-antibody Sandwich Method of ELISA） can determine precisely biological active inhibin B due to the use of the high specific antibody， which could meet the needs of scientific research and clinical diagnosis. The concentration of inhibin B changes with spermatogenetic malfunction. Therefore， spermatogenesis status can be assessed by measurement of inhibin B concentration. It has higher sensitivity and specificity in differential obstructive and non-obstructive azoospermia.

Key words: Inhibin B, Spermatogenesis, Follicle stimulating hormone, Azoospermia