The introduction of the Athlete Biological Passport is a landmark in the fight against doping. Contrary to traditional toxicological anti-doping analysis, its aim is to detect the biological consequences of doping through the measurement of different specific biomarkers which generate individual profiles for each athlete. This new approach allows anti-doping organizations to convict those athletes showing abnormal profiles for the use (not the presence!) of even undetectable forbidden substances or methods. Additionally, these data can be used for other purposes: to conduct targeted conventional anti-doping tests on those athletes showing unusual results and to evaluate the prevalence of doping within a population of athletes. By now only the hematological biomarkers of blood doping have been validated, but in the future additional modules will be introduced to detect other forms of doping.