This review of the literature on the psychological and behavioral effects of anabolic-androgenic steroids (AS) first looks at aspects of the history and prevalence of AS use in competitive sports. Research suggests that one-quarter to one-half million adolescents in the United States have used, or are currently using AS. Some effects of androgens on the central and peripheral nervous systems are reported. Numerous studies have examined relationships between testosterone levels, mood and behavior. A pattern of association between plasma testosterone and both subjectively-perceived and observed aggressive behavior has been revealed. Results from studies examining the effects of androgen therapy in individuals with androgen deficiencies have been mixed. Some demonstrate significant, positive psychological changes with AS and others do not. Examination of the effects of mental health in athletes with AS shows that for the most part, individuals use AS to significantly improve appearance and/or performance beyond what would be expected from training alone. The effects of AS have been reported in relation to withdrawal symptoms. Withdrawal effects include mood swings, violent behavior, rage, and depression; possibly severe enough to lead to thoughts of suicide. Methodological shortcomings in the studies reviewed are discussed. A summary reviews the issues associated with AS use in light of the methodological limitations. Medical and legal concerns regarding the psychological and behavioral effects of AS are discussed. (LLL)