Performance-enhancing substances include dietary supplements, prescription medications, and illicit drugs. Virtually no data are available on the efficacy and safety in children and adolescents of widely used performance-enhancing substances. This statement is intended to provide a generalized but functional definition of performance-enhancing substances. The American Academy of Pediatrics strongly condemns the use of performance-enhancing substances and vigorously endorses efforts to eliminate their use among children and adolescents.