ntroduction: Gas chromatography is one of the methods for determining markers such as fatty acids in the metabolic pro cesses in the human body. We have developed a method for the determination of fatty acids in various pathological conditions, which includes the selection of a stationary phase and optimization of separation conditions. Objective: To evaluate the effectiveness of treatment of rickets in children using apricot oil and aevit by gas-liquid chromatog raphy. Methods: The composition of higher fatty acids in blood serum in 87 children with rickets was determined by gas-liquid chroma tography. To identify the separated methyl esters of fatty acids, we used the __ampersandsignldquo;bystanders__ampersandsignrdquo; method and the method based on the __ampersandsignldquo;sorbent __ampersandsignndash; sorbate__ampersandsignrdquo; structural group components. A study of the composition of higher fatty acids in the blood serum was carried out in children with rickets - group I (38 sick children with rickets) undergoing the traditional method of treatment and group II (49 sick children with rickets) - with a combination of the traditional method of treatment with the use of modified therapy. Results: We found C(16:0)-palmitic, C(16:1)-palmitoleic, C(18:0)-stearic, C (18:1)-oleic, C(18:2)-linoleic, C(18:3)-linolenic and C(20:4)-arachidonic acids in blood serum. In the examined children with rickets, who received traditional treatment, lipid imbal ance was noted. The application of the modified method of treatment has shown its high efficiency and the indicators of the fatty acid composition of the blood returned to normal in the majority of children with rickets. Conclusion: Children with rickets have significant disorders of fatty acid metabolism. To correct the dismetabolism of higher fatty acids, along with traditional therapy, it is recommended to prescribe a modified method of treatment using apricot oil and aevit, which ensures high efficiency of therapy in children with rickets.