Purpose -This study suggests that informal practices and institutions of post-Soviet countries differ from informality in other post-socialist regions and, therefore, proposes categorizing it as 'post-Soviet informality' -a composite definition that extends beyond the concept of 'informal economy' and encompasses, along with economic activities, social and political spheres.Design/methodology/approach -The arguments of the paper are based on a comprehensive analysis of secondary sources.Findings -This article shows that, owing to the effects of antecedent regime's legacies and the problems of post-communist transition, for the proper analysis of informality in post-Soviet countries it needs to be based on an own concept.Originality/value -This study, in contrast to the existing literature on informality in post-communist spaces, specifically focuses on the informal sphere of post-Soviet countries, suggesting that the informal institutions and practices thriving across the vast post-Soviet space not only differ from the informal spheres elsewhere in the world, but also from informality in other post-communist regions.