Studies over the last decades have shown that microplastic pollution along with other factors of the anthropogenic impact may have a negative effect on the biological productivity of water bodies, including fluctuations in the numbers and biomass of commercial populations. Due to this ecological problem’s relevance, microplastics were first time surveyed on the Lake Ilmen in May, 2024. The study was carried out throughout the lake, and surface water sampling was made for microplastic particles content using a Manta trawl (335 μm). Analysis of pollutants at 15 stations revealed the presence of synthetic polymer particles, organic-and inorganic components, as wel as semi-synthetic fibers in the water samples. This is indicative of the lake micro-scaled pollution, as the found contaminants, including fibers, may pose a potential threat both to single species of aquatic bioresources living in the reservoir and to its ecosystem as a whole. Our quantitative assessment of the concentrations of microplastics and particles of various nature in the Lake Ilmen waters indicates negligible microplastic pollution, not exceeding 0.02 pcs/m3. These results can be used as a background (baseline) level for further studies of environmental risk from exposure to microplastics in the Great Lakes of northwestern Russia, which are of commercial fishery importance, as well as in other reservoirs of the Novgorod region.