Megestrol acetate (INN, USAN, BAN, JAN) (abbreviated as MGA or MA, and sold mainly under the brand names Megace and Megace ES), also known as 17α-acetoxy-6-dehydro-6-methylprogesterone, is a steroidal progestin and progesterone derivative (specifically, a 17-hydroxylated progesterone) with predominantly progestational and antigonadotropic effects. Though sometimes referred to simply as megestrol, it is important to clarify that megestrol acetate is not the same as megestrol, which is a closely related but different compound.