ENA common problem in the development of Estonia, Latvia and Lithuania in the post-Soviet period is depopulation caused by natural decline and migration outflow of the population. The decrease in numbers occurs both in the titular population of these countries and in all ethnic groups. But the rates of this reduction are different depending not only on external migrations, but also on the processes of natural reproduction of these groups. The aim of the study is to identify the main trends and features of the dynamics of the most numerous ethnic groups in the Baltic countries since 1959, as well as to assess the prospects for the natural reproduction of ethnic groups until 2061. The work uses sta tistical and graphical methods, but the novelty of the study is related to the analysis of the results of the forecast of ethno-demographic processes in the Baltic countries for the next four decades. As a result of the study, the main ethnic communities of Estonia, Latvia and Lithuania were divided into groups depending on the population dynamics in the Soviet, post-Soviet and forecast periods. The first group is formed by Russians, Belarusians and Ukrainians, a significant increase in the number of which in the Soviet period was associated with migration inflow, in the post-Soviet period there was a sharp decrease in the number due to migration outflow, in the forecast period this trend is expected to continue, but already due to the aging of the population. Sufficiently specific types of population dynamics over ten-year intervals characterize such ethnic groups as Poles, Jews, and Finns. Separately, the dynamics of the number of titular ethnic groups of the Baltic countries was considered.They are characterized by a slight increase in the number in the Soviet period, a not very significant reduction in the post-Soviet period, and the persistence of this trend due to the aging of the population in the forecast period. In all three Baltic countries, the share of titular ethnic groups is expected to continue to grow. Keywords: ethno-demographic processes, ethnic groups, assessment of reproductive potential, the Baltic states, Soviet period, post-Soviet period. [From the publication]