Introduction. The problems of an adequate assessment of the differentiation of Russian regions are relevant insofar as to ensure the sustainability of economic growth and socio-economic development need to mitigate economic and social disparities between regions. The article is devoted to methodological aspects of the comparative analysis of per capita incomes in Russian regions. This indicator can be considered both as a condition for the formation of strategies for the behavior of economic agents, and as a benchmark for the implementation of models of economic behavior. Theoretical analysis. In the study of regional inequality is particularly acute problem of weighting of per capita regional indicators of the share of the region’s population in the country’s population. Nominal incomes of the population do not take into account the heterogeneity of the Russian regions in terms of prices. The advantages and disadvantages of weighted and unweighted estimates in the study of interregional inequality. Empirical analysis. The results are based on the data of the Federal State Statistics Service of the Russian Federation. For inter-regional comparison of purchasing power of the population proposed a modified cost of living index. The dynamics of the coefficient of variation of per capita and adjusted for the modified index of the cost of living of the average per capita monetary incomes of the population is shown. A grouping of the regions of the Russian Federation according to the level of the adjusted average per capita income of the population. Results. The conclusion about the justification of the transition to the comparable purchasing power of income. Confirmed the declining trend in the dispersion of per capita incomes, that is sigma-convergence of Russian regions. In addition, the conclusion was confirmed about equalization of inequality, mainly due to the accelerated growth of incomes of the population of “poor” regions.