Abstract: In children with rickets, significant changes in the composition of higher fatty acids in blood serum have been established by gas-liquid chromatography. The depth of changes in the composition of higher fatty acids depended on the severity of the disease. The violated composition of higher fatty acids was corrected using vegetable (apricot) oil and aevit. Apricot oil helps to normalize the activity of serum lipase and leads to the restoration of the metabolism of higher fatty acids, the absorption of calcium and phosphorus thereby ensures high efficiency of therapy in children with vitamin D-deficient rickets. The effectiveness of this method of treating children before traditional therapy is shown. Abstract: In children with rickets, significant changes in the composition of higher fatty acids in blood serum have been established by gas-liquid chromatography. The depth of changes in the composition of higher fatty acids depended on the severity of the disease. The violated composition of higher fatty acids was corrected using vegetable (apricot) oil and aevit. Apricot oil helps to normalize the activity of serum lipase and leads to the restoration of the metabolism of higher fatty acids, the absorption of calcium and phosphorus thereby ensures high efficiency of therapy in children with vitamin D-deficient rickets. The effectiveness of this method of treating children before traditional therapy is shown.