This work is devoted to the study of the dynamics of changes in phytotoxicity of oil-contaminated meadow soils in the process of microbial bioremediation. The research was conducted in laboratory and field conditions. Winter rye (Secále cereále) was selected as the test object. To assess the degree of toxicity in the laboratory, the indicators of seed germination – germination rate and germination energy-were determined. In a field experiment, the ecological state of oil-contaminated soils was evaluated by the germination rate and the amount of aboveground plant biomass. Research results showed that the content of petroleum products significantly affected the percentage of germination of rye seeds. There are differences in the size of seedlings for different experimental schemes: in all tests, the average height of cleoptila on polluted soil was less than on unpolluted soil, but at the same time it differed for different experimental bioremediation schemes. The use of potassium humate and modified vermiculite as additives significantly reduced the toxicity of oil-contaminated soil.