The objective. Assessment of the dynamics of oxidative stress markers in the oral cavity in children with neuropsychiatric pathology after oral antioxidant therapy with vitamins С and Е. Patients and methods. The study included 72 patients with neuropsychiatric diseases (aged 7–17 years) and 56 somatically healthy children of the same age. In all children with neuropsychiatric diseases (mental retardation, Down’s syndrome, autism with mental retardation, infantile cerebral palsy with mental retardation, and schizophrenia) the signs of oxidative stress of varied degree were found in the oral cavity. The dynamics of the parameters of oxidative stress in the oral cavity was studied against the background of daily treatment with antioxidants (vitamins Е and С) for 4 months. Результаты. Before treatment, in the oral fluid of children with neuropsychiatric disorders a growth of the key markers of oxidative stress was found: catalase 40.6 ± 5.4 μmol min–1 g(protein)–1 (in controls 28.75 ± 4.5 μmol min–1 g(protein)–1), superoxide dismutase 29.9 ± 3.7 act. g(protein)–1 (in controls 16.55 ± 2.4 act. g(protein)–1), maximum chemiluminescence flash 0.146 ± 0.029 c.u. (in controls 0.035 ± 0.016 c.u.), chemiluminescent area 0.284 ± 0.023 c.u. (0.135 ± 0.013 c.u. in controls) and a decrease of the integral parameter of the functioning of anti-radical defence enzymes to 27.7 ± 12.1 cond. units. CAT/SOD compared with the similar parameter in the control group 101.9 ± 19.9 cond.units CAT/SOD (p < 0.05). After antioxidant therapy, the activity of antioxidant defence enzymes and the parameters of the state of low-molecular antioxidants significantly, maximally approaching the control values (p < 0.05). The value of the integral parameter of the functioning of anti-radical defence enzymes in children with psychoneurological diseases increased after antioxidant therapy by 73.6% (p < 0.05). Conclusion. We have established a restoration of the activity of low-molecular antioxidants and enzymes of antioxidant defence of oral fluids in children with neuropsychiatric disorders after antioxidant treatment. © 2019, Dynasty Publishing House. All rights reserved.