Children with Crohn's disease (CD) are at high risk for developing nutritional deficiencies. According to studies in adult patients with CD, loss of lean and skeletal muscle mass and decreased bone mineral density (BMD) are unfavorable prognostic factors for the course of the disease; among children, the prevalence of these changes has not been sufficiently studied as yet. The purpose of this research was to study the frequency and correlation between disorders of body composition and decreased bone mineral density in children with CD. Materials and methods used: medical records of 163 aged 5 to 17 y/o with a confirmed CD diagnosis were assessed for the risk of nutritional deficiency using STRONGkids screening tool, anthropometric parameters, body composition with bioimpedance measurements as well as the disease activity index with PCDAI and endoscopic activity with SES-CD. BMD was assessed in 145 using densitometry. Results: depending on the degree of risk of malnutrition, children were divided into 2 groups as follows: G1 with high and G2 with moderate risks for malnutrition. G1 patients had significantly lower values of both anthropometric indices (Z-scores BMI/age, mid-upper arm circumference/age) and lean and skeletal muscle mass (p<0.001) along with more severe course of CD according to PCDAI (p<0.001). According to bioimpedansometry data, a significant increase in catabolic processes was found in G1 children as a decrease in Z-scores for both the phase angle (p<0.001) and the active cell mass (p<0.001). A decrease in BMD was detected in 9 (37%) of G1 and 26 (21.4%) of G2. A correlation was found between Z-scores lean body mass/age and BMD/age (p<0.001, Rs=0.612). Among children with reduced BMD values, the indicators for BMI, lean, skeletal muscle and active cell mass according to bioimpedance measurements were significantly lower (p<0.001). Conclusion: the data obtained during the study proposes high incidence of decreased bone mineral density along with pathological changes in body composition in children with CD. The use of STRONGkids tool to identify children at high risk of developing malnutrition, especially in the absence of the technical ability to conduct a detailed assessment of nutritional status with determination of body composition and BMD indicators, makes it possible to timely identify patients requiring individual nutritional support aiming to optimizing diets and, if necessary, prescribing addition of specialized food supplements.