Long-term effect of Cenomanian solutions on the size and structure of soil nematodes communities were studied in natural conditions. Spills of highly mineralized waters from Cenomanian layers, which are used to maintain reservoir pressure, are dangerous for the environment. As a result of accidents there is salinization of soil and degradation of vegetation. For the study, the authors have chosen mixed forest on the right bank of the Tom River. The research estimated population dynamics of soil nematodes when exposed to highly mineralized solutions. The total number of nematodes during the study period changed over a wide range. The minimum of 1347 ind./100 g was registered in April while the maximum of 14554 ind/100 g was reached in May under the soil contamitation by highly mineralized solutions with the concentration of 200 g/kg. Taxonomic composition of nematode communities was studied as well. The researchers have found 26 genera that form the basis of nematode communities in unpolluted areas of light-gray forest soils. The influence of the Cenomanian solutions leads to the elimination of several genera of nematodes. The number of taxa varied from 20 to 21 depending on the solution concentration. Bacteriotrophs are the dominant group of the soil nematodes according to the number of taxa in the reference area. When Cenomanian solutions influece the communities of nematodes, 3 types of bacteriotrophs eliminate i.e. Prismatolaimus, Mesorhabditis and Acrobeles . Plant associated nematodes vary in quantity, as for the number of genera it does not change regardless of the concentrations of Cenomanian solutions added to the soil.The study established a negative impact of highly mineralized solutions which change the structure of soil nematodes communities.