Melengestrol acetate-d6 is the deuterium labeled Melengestrol acetate. Melengestrol acetate is a progesterone derivative, acts as an orally active corticosteroid hormone to promote endometrial proliferation, pregnancy maintenance, and delay of menstrual activity[1]. Melengestrol Acetate is used as a contraceptive agent for growth promoting effects and suppression of estrus in animals. Melengestrol acetate inhibits both the androgen-dependent and -independent prostatic tumors in vivo and can be used for cancer research[2].