Blood doping, through the increase of red cells, induces changes of hematological parameters. The aim of the Biological Passport is first to analyse individual longitudinal profiles in order to identify, through variations of the specific parameters, doping manipulations. Additionally, on the basis of abnormal values or profiles, athletes can be targeted for traditional anti-doping tests in order to detect forbidden substances or methods. We report the experience of the International Cycling Union in applying the Biological Passport to target athletes for the presence of erythropoiesis stimulating agents. All positive results which have been reported between 2008 and 2010 concerning athletes enrolled in the Biological Passport program are presented. Four cases are discussed more in details. To conclude, we propose possible ways of using the Biological Passport in order to better understand athletes' doping modalities, so that testing programs efficiency can be improved. Copyright ? 2012 John Wiley & Sons, Ltd.