The aim:Tostudythedynamicsof thelevelof 25(ОН)D, ІL-4, ІL-10, and IgG in the bloodserum of children with allergicdiseasesandtostudytheclinicaleffectof vitamin D3 administration n different dosage in this category of patients. Materials andmethods: 153 children aged 3-16 with such allergicdiseasesasbronchialasthma, atopicdermatitisandallergicrhinitis havebeen examined. The level of 25(ОН) D was determined using the electrochemiluminescence method, while the levels of ІL-4, ІL-10 and IgG were assessed using enzyme-linked immunoassay. Results: In the contrasting of the initial level of 25(ОН)D in the blood serum of patients after administration of 2,000 IU of vitamin D3 over 2 months, after summer and after treatment with cholecalciferol in higherdoses (4,000-5,000 IU) over 2 months, significant difference wasestablishedbetween the indicators by the Friedman criterion (λ2 = 41.211; P < 0.05). In thesimilar contrasting of ІL-4 indicators, a significant difference between them was traced (P < 0.05) in the period of acute disease as well as the downward tendency in the period of remission. In the similar contrasting of ІL-10 indicators, a significant difference between them was traced (P < 0.05) in the acute period and in the period of disease remission. In the similar contrasting of IgG indicators, adownward tendency was tracedin theperiodof acutedisease and significantdecrease (P < 0.05) - in the period of disease remission. In thecontrasting of 25(ОН)D and ІL-4, ІL-10 figuresastrongreversecorrelation relationship was traced. The therapeutic effect of the administration of vitamin D3 medication in different doses in children with allergic diseases was traced. Conclusions: The data obtained shows that in the treatment of children with bronchial asthma, allergic rhinitis and atopic dermatitis the complex therapy should include vitamin D3 medications in different doses within a long-term course of treatment.