Hydromadinone acetate (developmental code name NSC-33170), also known as chloroacetoxyprogesterone (CAP), as well as 6ñ-chloro-17ñ-acetoxyprogesterone or 6ñ-chloro-17ñ-acetoxypregn-4-ene-3,20-dione, is a steroidal progestin of the 17ñ-hydroxyprogesterone group that was never marketed. It is the C17ñ acetate ester of hydromadinone, which, similarly, was never marketed.