Tapeworms Ligula intestinalis is a wide distributed parasite species. Plerocercoids L. intestinalis has high epidemiological significance for fish health. In this study we obtained new data on the occurrence of plerocercoids of L. intestinalis from roach Rutilus rutilus in Kostomukshskoye Lake (Northern Karelia) and Murmansk Region (Northwestern Russia) using two mitochondrial genes (cyt b and COI). Both samples identified as the Ligula intestinalis Lineage A sensu Nazarizadeh et al. (2023).