On the territory of Cisbaikal region, 433 species of lichens have been identified, including 11 lichenicolous and 14 species of saprophytic fungus. In applying the ecological–zonal principle, four geographical elements were distinguished in the lichen flora: Arctic–alpine, boreal, nemoral, and multizonal, which in turn were subdivided into five distribution groups (arealogical groups): multiregional; Holarctic; Eurasian–North American; Eurasian, and Asian. The epiphytic lichen flora of the Cisbaikal region underwent a long period of formation, closely associated with the stages of formation of the vegetation cover, and is boreal, significantly enriched with representatives of the nemoral element; in addition, the vast areas of mountain structures in the region determine the presence of Arctic–alpine species in the flora. The overwhelming majority of the identified epiphytic lichens have wide ranges, covering the entire Holarctic or extending beyond it, which indicates the predominance of migration processes in the formation of the lichen flora and its weak geographic isolation. Keywords: epiphytic lichens, Cisbaikal region, distribution, geographical elements, arealogical groups.