This article discusses substances/techniques that target the brain in order to enhance sports performance (known as “neurodoping”). It considers whether neurodoping in mind sports, such as chess, is unethical and whether it should be a crime. Rather than focusing on widely discussed objections against doping based on harm/risk to health, this article focuses specifically on the objection that neurodoping, even if safe, would undermine the “spirit of sport”. Firstly, it briefly explains why chess can be considered a sport. Secondly, it (...) outlines some possible substances/methods that could be used in order to enhance chess performance and justifies the article’s focus on one potential form of neurodoping in particular – “mental stamina enhancement”. Thirdly, this article casts doubt on certain arguments that mental stamina enhancement would be unethical and contrary to the spirit of sport (as defined by WADA). This article stresses the importance of distinguishing the ethical argument that doping violates the “spirit of sport” from the definitional objection that once doping becomes routine in a certain “sport”, it would not count as a sport anymore. The fourth section discusses the definitional objection and argues that mental stamina enhancement in chess might disqualify chess from being a “sport” (according to traditional, rather than revisionist definitions of sport). Yet, it argues that this definitional objection does not provide strong enough grounds to justify the state or sports authorities imposing severe penalties (such as criminalisation or life-long suspensions from competing) for non-harmful neurodoping. The fifth section of the article argues that criminalising non-harmful neurodoping would be disproportionate. (shrink)