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 17a-acetoxy-6-dehydro-6-methylprogesterone, is a steroidal progestin and progesterone derivative (specifically, a 17-hydroxylated progesterone) with predominantly progestational and antigonadotropic effects.