The paper describes cyanobacterial assemblages in relation to mosses and vascular plants forming mosaic communities in Arctic tundra. The study area is located in the north of the Hornsund fjord. In the selected 14 type of habitats, the study analyzed the quantitative and qualitative share of cyanobacteria, mosses and vascular plants. Due to their similarity in cyanobacterial assemblages and their relations to vegetation, they were divided into 10 groups. Each group was characterized by a particular combination of species with a distinguishing cyanobacteria dominant species and mosses and vascular plants. The significant role of cyanobacteria crusts and mats in the formation of the Spitsbergen tundra suggests they should be included in the descriptions of communities present in the region.