Abstract: A series of derivatives of methyltestosterone was prepared by saturating the double bond to give the 5β-configuration. The androgenic and anabolic activities of thcse com- pounds were assessed in castrated mice by examining the weights of the seminal vesicles, the levator ani-bulbocavernosus muscles, and the kidneys. The 5β-configuration practically abolishes the androgenicity and anabolic effect of these compounds, whether they were given parenterally or orally. Besides, these com- pounds did not elevate the RNA content of the kidneys and levator ani-bulbocarvanosus muscle, nor did they increase the glycogen content of the levator ani-bulbocarvanosus muscle in castrated mice.