Etynodiol, or ethynodiol, is a steroidal progestin of the 19-nortestosterone group which was never marketed. A diacylated derivative, etynodiol diacetate, is used as a hormonal contraceptive. Etynodiol is sometimes used as a synonym for etynodiol diacetate.

It was patented in 1955.

Etynodiol is a prodrug of norethisterone, and is converted immediately and completely into norethisterone. Etynodiol is an intermediate in the conversion of the prodrug lynestrenol into norethisterone.

Etynodiol is a 19-nortestosterone derivative. Structurally, it is almost identical to norethisterone and lynestrenol, differing only in its C3 substituent. Whereas norethisterone has a ketone at C3 and lynestrenol has no substituent at C3, etynodiol has a hydroxyl group at the position.

Etynodiol is the generic name of the drug and its INNTooltip International Nonproprietary Name, while ethynodiol is its BANTooltip British Approved Name.