In the context of sport, an ergogenic aid can be broadly defined as a technique or substance used for the purpose of enhancing performance. Ergogenic aids have been classified as nutritional, pharmacologic, physiologic, or psychologic and range from use of accepted techniques such as carbohydrate loading to illegal and unsafe approaches such as anabolic-androgenic steroid use. The efficacy of many of these techniques is controversial, whereas the deleterious side effects are clear. The purpose of this article is to review the epidemiology, administration, efficacy, pharmacology, and side effects of commonly used ergogenic aids. Physical therapists should be able to recognize the signs of ergogenic aid abuse in individuals under their care, and they should be aware of the side effects of these aids. Moreover, the physical therapist can serve as a resource for those individuals seeking information on the risks and benefits of ergogenic aids.