A list of bryophytes of the State Nature Monument “Gora Vaida” (“The Vaida Mountain”), supplemented by a brief phytogeographic overview, is presented. It includes 57 species of hepatics and 138 of mosses. The flora is predominantly boreal with a number of East Asiatic and arctic-alpine species. The mountain is formed by limestone, which is rare in Sakhalin; so many species have here quite isolated populations. Sauteria japonica (Shimizu et S. Hatt.) S. Hatt. is recorded for the first time for Russia. Many northern species, e.g. Arnellia fennica, Eocalypogeia schusteriana, Tomentypnum nitens, Scorpidium cossonii, Catoscopium nigritum, Meesia uliginosa, etc. were found new to Sakhalin, occurring at ridge top in mossy tundra-like communities.