This article reviews the recent literature on the use of anabolic-androgenic steroids (AAS) for performance enhancement. Recent studies utilizing supraphysiologic doses of testosterone have demonstrated increases in strength and improvements in body composition, despite earlier assertions by the medical community that steroids were ineffective as ergogenic aids. Although data that support the theory of conversion of prohormones, such as androstenediol, to testosterone in the body is available, support for testosterone precursors alone as ergogenic aids is lacking. Drug testing laboratories are utilizing new techniques that analyze carbon-13 levels of urinary steroids to detect exogenously administered steroids as well as the use of urine-manipulating agents. Investigations that seek to refute athletes' various claims for positive drug tests are ongoing. The recent discovery, character-ization, and development of a urine test for tetra-hydro-gestrinone, a designer steroid, has brought the issue of performance enhancement once again into the public spotlight. Increasing attention is also being paid to the long-term effects of AAS abuse, as more authors characterize the changes to hematologic, hepatic, lipid, and hormone profiles as a result of years of steroid use. Although the understanding of AAS and testosterone precursors as performance-enhancing drugs continues to advance, there are likely to be more revelations as scientific investigations continue.