The paper focuses on the problem of identity and its determinants of the inhabitants of the Polish-Russian borderland. The state of research on the identity of the inhabitants of the Kaliningrad Region and the Warmia and Mazury Region (Western, Russian and Polish scientists) is reviewed. The concept of the borderland in the context of the cross-border cooperation idea is presented. The short history and uniqueness of the new Polish-Russian borderland is analysed with compact reference to the heritage of the earlier German and then Soviet influence. The specific features of the Regions (the Kaliningrad Region and the Warmia and Mazury Region) in the context of regional identity are emphasised. The features and determinants of the newly formed self-perception and regional identity are characterised (among others official symbols, place names, historical writings, attitude to the state and homeland) in the perspective of the common European space (European Union) and Polish-Russian bilateral relations. Such approach is connected with presentation of the concept of regional identity and the “positive legend” on the Polish-Russian borderland.