[in Belarusian with English abstract: ] 360 lichen specimens of the genus Lepraria collected in Belarus by different scientists during 1957-2015 and housed in GRSU, GSU, MSKH, MSKU and MSK herbaria were studied by thin layer chromatography. 71 specimens contain fatty acids and appear to be Lepraria jackii (69 samples) and Lepraria rigidula (2 samples). The latter species is new to the county. Their morphological description and chemistry are provided in the article. The data obtained clarify the ecology and distribution of these species, both within our country and Europe. Key words: lichen, Lepraria jackii, Lepraria rigidula, biodiversity, chemotaxonomy, thin-layer chromatography, secondary metabolites, fatty acids.