Cyanophages of the family Myoviridae were studied in Lake Hovsgol based on the analysis of g20 gene fragments. The analysis revealed the diversity of g20 cyanomyovirus sequences in Lake Hovsgol. It was found a great similarity of genes from the Lake Hovsgol and Lake Baikal. Distribution of closely related virus strains in these water bodies is attributed to close geographical location, direct water connection and similar hydrochemical parameters of the lakes.