The disclosure of repeated cases of athletes who abuse performance-enhancing drugs is an ordinary phenomenon in the athletic community. In addition, the completion of sequencing of the human genome and the unprecedented advances in molecular biology have enabled the progression from traditional drug enhancement to hypothetical (at present) gene transfer. Scientific, sports, and antidoping authorities fear that gene doping will be the next major challenge. The misuse of gene therapy to improve athletic ability, which is commonly referred to as "gene doping," represents a practice as dangerous and unethical as any type of conventional doping. However, gene doping appears to be more attractive than traditional forms of doping because it is still undetectable and thus much less preventable. This review focuses on gene doping, the risks involved, and the ethical issues that emerge. It also discusses the possible strategies that can be used to detect this new form of doping.