Fluoxymesterone (Halotestin) is an anabolic steroide with strong androgenic properties that has been used in the treatment of male hypogonadism, delayed puberty in males, and in the treatment of breast neoplasms in women. It is approximately 5 times as potent as methyltestosterone. The antitumor activity of fluoxymesterone appears related to reduction or competitive inhibition of prolactin receptors or estrogen receptors or production.