Performance enhancing drugs, ergogenic aids, and supplements come in many forms. The financial, personal, social, and health-related impact of these substances has wide and varied consequences. This article reviews common substances and practices used by athletes. It discusses the history, use, effects, and adverse effects of androgenic anabolic steroids, peptide hormones, growth factors, masking agents, diuretics, volume expanders, β-blockers, amphetamines, caffeine, other stimulants, and creatine. The evidence base behind the use, safety, and efficacy of these items as well as testing for these substances is discussed.