Abstract. The twentieth anniversary of Russian-Byelorussian integration was celebrated in December 2019. Its legal basis is the Agreement of creation of the Union state of Russia and Belarus. During the integration period the countries have made significant progress in developing cooperation in the fields of security and foreign policy, trade, economic and interregional relations as well as in implementing innovative scientific and technical programs and large-scale humanitarian projects. The positive experience gained within the Union state is actively used in the broader format of the Eurasian Economic Union (EEU). Despite the existing difficulties in relations between Russia and Belarus, the potential for the development of the Union state is not completely exhausted.