Objectives A characteristic feature of sport since ancient times is competition and the will to win. The basic criteria for the division of competition are goal, discipline and gender. In the last three decades the gender division of athletes has been the most controversial. Material and methods It is caused by the increasing participation of transgender people in sports competitions, especially in women's disciplines. The aim of the study is to summarize all the arguments used in the discussion on the participation of transgender people in sports competitions. Will the inclusion of transgender people in women's sports not cause the twilight of women's sports? Results The research hypothesis is the statement that it is necessary to search for a solution for the willingness of transgender people's participation in sports competitions. The unquestionable right of these people to train sport must be however confronted with the right to fair competition based on equal opportunities. The study uses the method of analyzing specific cases, the analysis of international law, sports organization law and Polish law. Conclusions Last but not least, elements of the legal-historical method is used to present the perspective of the development of public discussion and legal regulations concerning the participation of transgender people in professional sport. The result of the work is the presentation of specific solutions to this issue.