Anti-doping practices inevitably intrude on athletes' informational private sphere. How far can the fundamental right to data protection be limited in modern sport? This work seeks to strike a balance between the fundamental principles of data protection law, on the one hand, and the necessity of anti-doping measures, on the other. It focuses on the main issues of compliance of anti-doping activities with the General Data Protection Regulation and international standards, the legitimacy of processing personal data in pursuit of a legitimate aim - the fight against doping, and the important safeguards for the ensuring protection of athletes' personal information. The work takes into account the recent developments in the European law and the anti-doping framework, as well as the recent jurisprudence from the European Court of Human Rights.