Mesterolone is an anabolic steroid indicated in the treatment of low testosterone, hypogonadism, oligozoospermia, and Leydig cell failure. Mesterolone is a synthetic anabolic-androgenic steroid (AAS) and derivative of dihydrotestosterone (DHT). It is inactivated by 3α-hydroxysteroid dehydrogenase in skeleta muscules so it is considered a weak androgen. It is not a substrate for aromatase so it is not converted into estrogen. Mesterolone demonstrated to have minimal effect on sperm counts and levels of FSH or LH 1,2. Experiments of mesterolone serving as a potential treatment of depression are still undergoing.