Boldenone (1,4-androstadiene-3-one-17β-ol, available as the undecylenate ester) is an anabolic steroid developed for veterinary use, mostly for treatment of horses. It is not indicated for use in humans in the US and is only available through veterinary clinics. The activity of boldenone is mainly anabolic, with a low androgenic potency. It has a very long half-life, with minimal blood levels present up to 8 weeks after discontinued use. Boldenone will increase nitrogen retention, protein synthesis, increases appetite and stimulates the release of erythropoietin in the kidneys. The drug is commonly used in doping within bodybuilding. If intended to assist in bodybuilding, the drug is taken as part of a steroid stack of other anabolic steroids, usually with a potent androgen like testosterone as the ‘base’ of the stack.