Bodybuilders and athletes have recognised for several decades that the use of anabolic steroids can promote muscle growth and strength but it is only relatively recently that these agents are being revisited for clinical purposes. The pharmacology of anabolic steroids is not well understood, although intracellular steroid metabolism and also the topology of the bound androgen receptor interacting with co-activators are considered to be important factors. Behavioural changes by genomic and non-genomic pathways probably help motivate training. Doping with anabolic steroids can result in damage to health but it is important for endocrinologists not to exaggerate the risks but to emphasise to users that an attitude of personal invulnerability to their adverse effects is certainly misguided. Despite the large number of xenobiotic anabolic steroids available, testosterone continues to be the most common adverse finding in drug control tests undertaken by World Anti-doping Agency accredited laboratories. The detection of testosterone administration, nonetheless, remains challenging and a number of analytical approaches are now advocated, including using the individual as his own reference, a so-called athletes biological passport, and determination of steroid carbon-isotope ratio signatures.