The issue of democracy in the countries of post-Soviet space is of particular interest to the scientific and expert community. Not the last role in these processes was played by the escalation of the number of ethnic conflicts that have taken place in the territories of these countries. However, the American political scientist M. Mann has offered a new perspective on processes of democratization. He developed the concept of “the dark side of democracy”. According to the author, democracy can be seen not only in the traditional sense as “people power”, but as “the power of a particular ethnic group”. In the second approach, widespread ethnic cleansing that occur in the course of the development of conflicts at the national (religious) grounds. Аll the negative feelings, from class to religious hatred is a reason for the intensification of ethnic nationalism. In the case of escalation of conflict, he began to absorb particular components of ethnic confrontation (favoritism in respect of individual group members, discrimination against outsiders the existence of ethnic tensions, the presence of horizontal inequalities between culturally divided groups). While maintaining these trends, says M. Mann, we can say that the dark side of democracy is expressed in the perversion of the liberal or socialist ideals of democracy. According to M. Mann, at a time when certain ethnic or religious group (Turks, Hutus, Albanians) begin classify themselves as the true exponents of the popular will, is a perversion of the true democratic values and democracy as a whole. Referring to the experience of the Soviet Union, M. Mann notes that the role of such a “privileged” political actor in socialist societies the assigned classes. The analyst notes that a particularly brutal and bloody purge — a phenomenon of modernity, since in earlier times they were not as widespread as in the 80-90-years of the twentieth the twentieth century. As the most striking instance of the countries in which the concept of the dark side of democracy became widespread, the author of the article was chosen Yugoslavia (period 80’s-90’s of the twentieth century) and Ukraine (modern political processes in the country occurring since 2014 to present). These states were chosen because of the similarity of the processes of democratization, the presence of ethnic conflict (the confrontation between Albanians, Croats, Serbs in Jugoslavia and the Western and South-Eastern part of Ukraine), as well as the presence in both countries political actors seeking to justify pre-emptive right to the sovereignty of a particular territory.