Follicle-Stimulating hormone (FSH) is a glycoprotein produced by the pituitary gland and consists of two subunits with an approximate total molecular mass of 35 kDa. In males, FSH acts on the Sertoli cells of the testis to stimulate the synthesis of androgen-binding protein, which is indirectly involved in stimulating spermatogenesis. FSH also stimulates the secretion of inhibin, which acts by a negative feedback mechanism to inhibit further production of FSH by the pituitary. In females, FSH acts on the granulosa cells of the ovary to stimulate steroidogenesis, and to stimulate and sustain the development of a follicle leading up to ovulation. Cayman’s human Follicle-Stimulating Hormone ELISA Kit is an immunometric (i.e., sandwich) ELISA that permits FSH measurements within the range of 0.6-100 mIU/ml. This assay offers specific and sensitive analysis of FSH in human serum and has not been validated for other types of samples.