Algestone (), also known as alphasone or alfasone, as well as dihydroxyprogesterone, is a progestin which was never marketed. Another progestin, algestone acetophenide, in contrast, has been marketed as a hormonal contraceptive.
Algestone, also known as 16ñ,17ñ-dihydroxyprogesterone or as 16ñ,17ñ-dihydroxypregn-4-ene-3,20-dione, is a synthetic pregnane steroid and a derivative of progesterone and 17ñ-hydroxyprogesterone. Closely related analogues of algestone include 16ñ-hydroxyprogesterone, algestone acetonide, and algestone acetophenide.