The aim of the work was to increase the effectiveness of treatment of the severe asthma phenotype in school-age children, taking into account the diagnostic value of atopic reactivity indicators. The study involved 30 pupils with severe asthma and 30 children with moderate-heavy version of it. Amid severe asthma increases risk of higher concentrations of IL-4 and IL-5 in the serum, and almost in every second child was observed the increased concentrations of Ig E (more than 545,3 IU/mL, odds ratio was 1,9 (95 % CI 1,1-3,4). In the group of patients with severe asthma were significantly more frequent cases of the skin hypersensitivity to household allergens with respect to the members of the second group. There were separated the indices of clinical and epidemiological risk and diagnostic value of some markers of atopic reactivity for verification of the severe asthma phenotype. It was established that the development of severe asthma in children marked tendency to reduce the metabolic activity of eosinophilic granulocytes in blood (in terms of intracellular content of cationic proteins and peroxidase) and phagocytic ability of these effector cells of allergic inflammation. For the phenotype of severe asthma the risk of high concentration of IL-4 and IL-5 in serum increased in 3,1 times, but this paraclinical test is rather suitable for verification of this phenotype (SP – 84,6% (95 % Sp 75,9–91,1)) than for its detection (Se – 36,4 % (95 % CI 26,9–46,6)).