Abstract
The article is devoted to the study of twin-city relations as a component of the communication space of the Union State of Belarus and Russia. Their importance for enhancing the legitimacy of union-building and deepening bilateral integration is emphasised. The key formats of twinning are shown, taking into account the general process of institutionalisation of this integration. Parameters of quantitative and qualitative dynamics and positive changes are identified. Certain weaknesses are articulated, including insufficient regulatory support and alignment with integration benchmarks. Some corrective measures are proposed for the implementation of decisions taken in this area, their consolidation in union acts, information support for twin-city relations, and their public and political backing.