Relevance. The study of bioradical processes in periodontitis in the dynamics of the disease and the establishment of the role of predictors of periodontal tissue damage will provide a deeper understanding of the links of pathogenesis and, on this basis, introduce new therapeutic and diagnostic technologies into practice. The purpose of the study: Assessment of the level of markers of oxidative stress in experimental periodontitis in the dynamics of the study. Materials and methods. The study was conducted on white non-linear rats, reproducing the model of periodontitis proposed by Shkolnaya K. D., Atrushkevich V. G. (Patent RU No. 2625295 of 12.07.2017). The total activity of free radical oxidation and the body's antioxidant potential were evaluated by biochemiluminescence, the intensity of lipoperoxidation processes, and the enzyme antioxidant potential. Results. A comprehensive analysis of the overall oxidative and antioxidant capacity of the body was carried out, during which it was revealed that progressive experimental periodontitis causes inhibition of the antioxidant potential and is characterized by a violation of the processes of neutralization of reactive oxygen species and the inability to inhibit the launched reactions of free radical oxidation, as evidenced by the dynamics of an increased level of markers of oxidative stress. Conclusion. Thus, in periodontitis, oxidative stress develops, which contributes to the progression of destructive processes of periodontal tissues, which substantiates the feasibility of using markers of the intensity of free radical oxidation as diagnostic and prognostic criteria for the course of the disease and the introduction of antioxidant-type drugs in complex therapy.