As a result of our investigations, for the first time in Ukraine, the presence of trematodes agents at different stages of development (sporocyst, redia, cercariae and metacercariae) that parasitize in the body of freshwater mollusks Lymnaea stagnalis, Lymnaea (Radix) auricularis and Viviparus viviparus of the Chernobyl zone was established. The molluscs were collected for further study during an expedition to the Chornobyl Radiation and Ecological Biosphere Reserve. In order to study mollusks for the presence of larval stages of helminths, molluscs were collected in reservoirs of different types from two locations: near Lake Pereval, which flows into the Pripyat River and near Lake Bily (Ivankiv district of Kyiv region). On the first stage of the investigation, the molluscs were identified. Thus, as a result of our research we found 18 molluscs of the species Lymnaea stagnalis, 12 molluscs of Viviparus viviparus, 12 molluscs of Lymnaea (Radix) auricularis and 6 molluscs of the species Lymnaea truncatula.On the second stage, the molluscs were examined on the presence of parasitic organisms. As a result, among the studied 18 molluscs of the species Lymnaea stagnalis, 15 of them or 83.33 % had a significant quantity of trematodes at different stages of their development. The intensity of the invasion was 40 sporocysts, about 20 redia, 60 cercariae and 40 metacercariae. The metacercariae that were found morphologically were classified into 3 different species. Cercariae were identified as an agents of echinostomatosis. Among the 12 molluscs of the species Viviparus viviparus studied, 9 of them (75 %) had metacercariae trematodes with an invasion intensity 16 ± 8 in each of them. Of the 12 molluscs of the species Lymnaea (Radix) auricularis, 6 of them (50 %) showed a significant quantity of sporocysts and cercariae trematodes. None of the larval stages of trematodes were detected among the 6 molluscs of the Lymnaea truncatula species.According to the results of the research, for the first time in Ukraine the presence of different stages of development, such as sporocyst, redia, cercariae and metacercariae, were identified in the freshwater molluscs of the Chornobyl zone of radioactive contamination.Moreover, the invasion extent among the studied mollusks of the species Lymnaea stagnalis was 83.33 %, Lymnaea (Radix) auricularis –50.00 %, and among Viviparus viviparus – 75.00 %
freshwater molluscs, agents of parasitic diseases, Chernobyl radioactive contamination zonе