The authors present the formation and development of the Ukrainian national education system in Slovakia after the World War II, which was determined by its results and new political conditions. The founding of Russian schools in Eastern Slovakia did not correspond to the wishes of part of the Ruthenian population, and their preference was a source of permanent tension. The authors of this article analyse the personnel, material and technical problems related to the development of Ukrainian (Russian) schools as well as the activities of political and state authorities in their solution. The introduction of the Ukrainian language as the language of instruction disrupted the consolidation in this area and increased dissatisfaction in many municipalities. The efforts to persuade people or various administrative obstacles could not prevent the change of the language of instruction from Ukrainian to Slovak.