The most plausible line of anti-doping argumentation starts with the fact that performance enhancing substances are harmful and put at considerable risk the health and the life of those who indulge in the overwhelming promises these substances hold. From a liberal point of view, however, this is not a strong reason neither to morally reject doping altogether, nor to put a blanket ban on it; on the contrary, allowing adult, competent and informed athletes to have access to performance enhancement drugs is often showcased as a liberty-related right of noninterference. In this article I will first discuss doping from the liberal point of view, especially in the light of the harm principle as it was introduced by Mill and elaborated by his successors, most notably by Joel Feinberg. Then I will examine whether – and to what degree – one’s decision to receive performance enhancement drugs would mean to use humanity in one’s own person only as a means, which would be self-defeating in the light of Kantian ethics. From this I will move one step backwards to what I consider as the core question concerning the ethics of doping, the one that is logically prior to any other in my view, and concerns the consistency of the thesis that doping may be compatible with sport. I will argue that there is an inherent logical antinomy between doing sport and using performance enhancement drugs, one that presents any argumentation in favor of doping as essentially self-contradictory.