The work is devoted to the study of the dynamics of inequality of educational achievements and opportunities in the segment of school education in Russia and the countries of the Visegrad group. The study is based on the data of the «International Program for the Assessment of Educational Achievements of Students» (PISA) for 2003-2018. The methodology for assessing the inequality of possibilities is based on a parametric approach and ex-ante determination of the equality of possibilities. The scientific novelty of the work is determined by the fact that, in addition to studying the dynamics of educational achievements in the countries under consideration, an assessment of an important component of the inequality of educational achievements - the inequality of opportunities - is additionally carried out. The idea of dividing inequality into unfair and fair components is justified within the framework of the theory of equal opportunities developed in the second half of the twentieth century in Western social philosophy. The calculations carried out indicate that each of the countries under consideration is unique in its own way. The most problematic are Slovakia and Hungary, which demonstrate a tendency to decrease the average level of educational achievements and a high level of inequality of opportunities. Poland looks the most prosperous, with an increase in educational results and a decrease in inequality of opportunities. In the Russian Federation, there is a tendency to increase reading and mathematical literacy in the absence of progress in natural science. The level of inequality of opportunities in the Russian Federation is relatively low with a slight downward trend.