The article analyzes ethno-cultural, national, and social changes in the structure of the population of the Crimea in the second half of the 20th century and their influence on the ethnopolitical situation of the peninsula. This is the only region in modern independent Ukraine with the prevalence of ethnic Russians. Besides, they are first or second generation residents unlike mentally Ukrainized Russians in the Black Sea region or Donbas. The incorporation of the Crimea into Ukraine produced a positive effect on its socioeconomic and cultural development. As the All-Union population census of 1959 showed, the population of the peninsula grew to 1,201.5 thousand against 589 thousand people in 1945. Over the next 30 years, this number reached 2,430.5 thousand. The process of mass return of the Crimean Tatars, intensified in 1987, led to their significant quantitative increase on the peninsula, substantially changing the ethnic structure of the region. Crimean Tatars (12.1 %), Belarusians (1.5 %), Tatars (0.5 %). Among main determinants of the sociodemographic situation in the Crimea during the years of Ukraine’s independence, it is worth mentioning the mosaic structure of the ethnic composition of the peninsula population with the unconditional demographic dominance of Russians; the re-emigration processes (the return of Crimean Tatars, Armenians, Bulgarians, Greeks); the controversial nature of the Ukrainian-Russian relations.