(8R,9S,13S,14S,17R)-17-ethynyl-17-hydroxy-13-methyl-1,2,4,6,7,8,9,11,12,14,15,16-dodecahydrocyclopenta[a]phenanthren-3-one

Noretynodrel (INN), or norethynodrel (USAN, BAN), also known as 17α-ethinyl-δ5,10-19-nortestosterone or as 5(10)-norethisterone, is a steroidal progestin. It was introduced in 1957 in Enovid, a combination formulation of noretynodrel and mestranol, for the treatment of gynecological and menstrual disorders. A few years later, in May 1960, Enovid was also approved as the first oral contraceptive. In addition to its progestogenic effects, noretynodrel, unlike most progestins but similarly to etynodiol diacetate, also has some estrogenic properties. It has little or no androgenic action. In accordance, noretynodrel has not been found to virilize female fetuses, in contrast to most other testosterone and 19-nortestosterone progestins such as ethisterone, norethisterone, and norethisterone acetate.