A special place in the pathogenesis of recurrent aphthous stomatitis is occupied by the state of local immunity, which can affect the clinical course and prognosis of chronic diseases of the oral mucosa. The inflammatory process in recurrent aphthous stomatitis is initiated by stimulation of keratinocytes of the oral mucosa by a currently unknown antigen, which leads to stimulation of T-lymphocytes and the release of cytokines and various interleukins. Cytokines are the main nonspecific humoral factor of immunity, providing the initiation and development of an inflammatory response during the development of a protective immune response. A huge number of works are devoted to the study of cytokine status in recurrent aphthous stomatitis, which plays one of the key roles in the pathogenesis of the disease. However, most of the studies were conducted in patients over the age of 18, in addition, the results obtained are contradictory. This determined the purpose of this study – to assess the cytokine status of oral fluid in children with recurrent aphthous stomatitis. The study examined 70 children who were divided into 2 groups. The main group consisted of 45 children aged 7 to 14 years, patients with recurrent aphthous stomatitis, during the relapse of the disease. The main group was divided into 2 subgroups: A – 20 children with the duration of recurrent aphthous stomatitis up to 5 years, group B – 25 children with the duration of recurrent aphthous stomatitis more than 5 years. All patients in the main group had concomitant diseases, in most cases, diseases of the gastrointestinal tract. The control group consisted of 25 practically healthy children without recurrent aphthous stomatitis. In children with recurrent aphthous stomatitis in the oral fluid, a significant increase in the concentration of the anti-inflammatory cytokine TNF-α and a decrease in the concentration of IL-10, an imbalance in the level of IL-2 depending on the duration of the disease, as evidenced by a pronounced inflammatory process of the oral mucosa with epithelial destruction.