LH is a member of the pituitary glycoprotein hormone (GPH) family and consists of a non-covalently linked GPH α-subunit and hormone-specific β-subunit. The GPH α- and LH β-subunits contain a cysteine-knot motif and several N-linked glycosylation sites, both of which are important for biological activity. LH as well as FSH and CG has gonadotropic function and thus the grouping as gonadotropins. LH binds to LHR located on the plasma membrane of granulosa cells in the ovary and stimulates estrogen production, ovulation, and the development of the corpus luteum. In the testis, LH binds to LHR in Leydig cells and stimulates angrogen production and spermatogenesis. The synthesis and release of LH are regulated by GnRH and gonadal steroids. LH is implicated in hypogonadal dysgenesis and its urinary levels are useful in the prediction of ovulation. Recombinant human LH is used for treatment of infertility to stimulate follicular maturation.