In the lichen thalli of 6 Peltigera species and Nephroma arcticum enzyme-linked immunosorbent assay was conducted to investigate the distribution of low-molecular biologically active metabolites related to the group of mycotoxins, as well as the distribution of usnic acid at N. arcticum. Thirteen of micotoxins have been founds in the lichens.  Qualitative composition of mycotoxins varies in different species of Peltigera and P. aphthosa, collected in different years. Some mycotoxins showed statistically significant differences of their content in theand lower parts of the thalli of 4 Peltigera species and Nephroma arcticum.  The trend of higher accumulation of mycotoxins in the lower older part of the  thalli as compared with the younger ones was noted. Statistically reliable data on the higher usnic acid content in the younger of the thallus of N. arcticum as compared with the older was obtained.