Sphagnum mosses are a characteristic component of plant communities in the mountain mires of the Altai-Sayan region. The genus Sphagnum L. ranks first in the species diversity and includes 32 species, accounting for 57.1% of the species diversity of sphagnum mosses of Russia and 62.8% of the species diversity of sphagnum mosses of the Asian part of Russia. Twenty-five species of sphagnum moss are revealed in the mires of the Western Sayan and Altai, listed in this paper; 28 species occur on the Kuznetsky Alatau mires. Rare species are Sphagnum aongstroemii, S. auriculatum, S. contortum, S. platyphyllum, S. pulchrum, S. subfulvum, S. tenellum.