For twenty years, the Union State of Russia and Belarus has been one of the most durable integration associations in the post-Soviet space. In the framework of this article, the author explores the main stages of the historical formation and development of this integration formation, which had difficulties in its formation. The characteristic of the institutional structure of the Union State, its main bodies, both existing at the present time and those that are still supposed to be created, is given. Particular attention is paid to the current state of the Union State and possible scenarios of its development in the future. It analyzes the twenty-year history of the Union State of Russia and Belarus, the achievements and failures that were and are within the framework of this integration association. The contents of the Treaty on the Creation of the Union State as the main legal act that enshrines the basic principles and goals of its activities are disclosed in detail. The main governing bodies of the Union State, their composition and functions are described in detail. Particular attention in this context is paid to the activities of the Supreme State Council, the Parliamentary Assembly, the Council of Ministers, the Standing Committee and the Secretary of State of the Union State. Particular attention is paid to the current state of the Union State, the difficulties on the way of its development at the present time and the attempts that its participants are making for further closer integration of the two countries. The article describes the work within the Union State in terms of deepening currency integration, which ideally can lead to the introduction of a single currency in the Union. Scenarios of the possible development of the Union State in the future are shown. As a result, the author concludes that the Union State has far from exhausted itself, and the fact of its existence contributes and will contribute to a more dynamic development of Russia and Belarus, both now and in the future.