The anabolic-androgenic steroids (AAS) are a family of hormones that includes the natural male hormone testosterone and more than 100 other synthetic relatives of testosterone (Pope and Brower 2004). All AAS possess both anabolic (muscle-building) and androgenic (masculinizing) properties. Data from the National Household Survey on Drug Abuse (1994) suggest that about 1 million American men have used these drugs at some time. Although AAS use was once confined largely to elite athletes, increasing numbers of young men have now begun to use these drugs to gain muscle and lose fat, often simply for the sake of personal appearance (Kanayama et al. 2001). The majority of these men are in their 20s or 30s, with a minority starting AAS use as teenagers (Kanayama et al. 2007). Girls and women rarely use AAS because they are less likely to want to be muscular and because AAS use makes women subject to their masculinizing effects, such as beard growth, deepening voice, and masculinizing of sexual characteristics (Gruber and Pope 2000). Although some recent anonymous surveys have suggested that substantial numbers of females have used AAS (CDC, U.S. Department of Health and Human Services 2005), these surveys have likely produced inflated estimates as a result of false positive responses on questionnaires; the true number of female AAS users is likely very small (Kanayama et al. 2007). For these reasons, the following discussion will focus primarily on treatment of male AAS users, although the general principles expressed would presumably apply to the rare cases of female users as well (Gruber and Pope 2000).