Algestone acetonide (developmental code name W-3395), also known as algestone 16α,17α-acetonide or 16α,17α-isopropylidenedioxyprogesterone, is a progestin which was never marketed.[1][2] It is the acetonidecyclicketal of algestone.[1][2] Another progestin, algestone acetophenide, in contrast, has been marketed.[1][2]