Diatom composition in lakes of the Vangyr river basin in the Yugyd Va National Park is studied. 256 taxa from 38 genera, 16 families were identified. Among families, Naviculaceae (87 taxa; 34%), Fragilariaceae (36; 14.1%), Cymbellaceae (28; 10.9%), Achnanthaceae (21; 8%), Bacillariaceae (21; 8%), Gomphonemataceae (16; 6%), Eunotiaceae (14; 5.5%) predominate. The most diverse genera are Navicula, Fragilaria, Cymbella, Nitzschia, Pinnularia, Achnanthes, Gomphonema, Eunotia. Ecological and geographical analyses of diatoms are made. Results have shown the prevalence of cosmopolitans, benthic diatoms, alkaliphilous and indifferent to water mineralization species. Halophobic and halophilic species are in almost equal proportions. Difference between arctic and boreal diatoms shares is little.