Bolandiol (INN), also known as 19-nor-4-androstenediol, estr-4-en-3β,17β-diol, or 3β-dihydronandrolone, is an anabolic-androgenic steroid (AAS) that was never marketed. Bolandiol bound with lower affinity to the recombinant rat androgen receptor (AR) than the other androgens and had low, but measurable, affinity for recombinant human progestin receptors (PR-A, PR-B), and estrogen receptors (ERalpha and beta-1). Functional agonist activity was assessed in transcription assays mediated by AR, PR, or ER. Bolandiol that until recently was available as a dietary supplement used by athletes to enhance performance. Bolandiol is on the World Anti-Doping Agency's list of prohibited substances and is therefore banned from use in most major sports. It is a potential metabolic precursor to nandrolone. However, several clinical studies have concluded that bolandiol does not alter the strength, body composition, or exercise performance. Bolandiol suppresses gonadotropins and endogenous testosterone production.