The article presents the data ondistribution and defeat of gastropod mollusks by parasitic trematodes inbiotopes of small reservoirs (rivers, lakes and swamps) of the Dnipro basin ofnorthern regions of Ukraine. During the 2016-2017 years, at the following areaswere collected and identified: Lymnaea (L.) stagnalis (Linnaeus, 1758); L.truncatula (Müller, 1774); Planorbis (P.) corneus (Linnaeus, 1758); P.рlanorbis (Linnaeus, 1758); Viviparus contectus (Millet, 1813); Valvatapiscinalis (Müller, 1774) and Succinea pfeifferi (Rossmässler, 1834). The microscopicstudy of the mollusks’ liver allowed us to detect the presence of pathogens ofcattle trematodoses inside a certain number of the snails – Fasciola hepatica(Linnaeus, 1758) and Paramphistomum sp. (Fischoeder, 1901). At biotopes ofsmall rivers, 8.3% of mollusks L. truncatula species, 23.5% of L. stagnalis and5.7% of P. corneus were affected. At lakes and swamps, the number of affectedL. truncatula was 36.3%, and L. stagnalis – 13.7%. It was determined the defeatof ruminants with fasciolosis and paramfistomatoses in designated regions. Ittestifies to the formation of sustainable natural foci of these invasions.