Cismadinone (INN), also known as 6ñ-chloro-17ñ-hydroxypregna-1,4-diene-3,20-dione or 6ñ-chloro-ô<sup>1</sup>-dehydro-17ñ-hydroxyprogesterone, is a steroidal progestin closely related to the 17ñ-hydroxyprogesterone derivatives that was never marketed. An acetylated form, cismadinone acetate, also exists, but similarly to cismadinone, was never marketed.