Methylstenbolone, known by the nicknames M-Sten, Methyl-Sten, and Ultradrol, is a synthetic and orally active anabolic–androgenic steroid (AAS) and a 17α-methylated derivative of dihydrotestosterone (DHT) which was never introduced for medical use. It is a designer steroid and has been sold via the internet marketed as a dietary/nutritional supplement.