Objective. To estimate the annual cost of antibiotic therapy for cystic fibrosis exacerbations in children depending on nutritional status and the comparative cost of enteral nutrition products of two manufacturing companies. Patients and methods. This study included 50 male and female patients with cystic fibrosis aged 7 to 17 years (mean age 13 ± 4 years). All patients were divided into two age groups. Group 1 consisted of 26 children aged 7 to 10 years and group 2 consisted of 24 children aged 11 to 17 years. Each age group was subdivided depending on the body mass index (BMI): subgroup 1: ≤10th percentile, subgroup 2: 50th percentile. According to the 2019 registry, we calculated the number of courses and doses of antibiotic therapy per year, the annual cost of antibiotic therapy in each subgroup and per patient, and the cost of nutritional status correction with supplementary feeding. Results. In groups of patients with different nutritional status, it was shown that the average annual cost of antibiotic therapy in children aged 7–10 years with BMI ≥50th percentile was 600 thousand rubles (11%) lower than in children with BMI ≤10th percentile. In the age group of 11–17 years, cost savings amounted to 2.9 million rubles (58%). When calculating the cost of enteral nutrition, it was found that the use of domestic products to correct the nutritional status is economically more feasible. Cost savings ranged between 484,080 and 608,880 rubles (25–30%) in each age group. Conclusion. The decline in nutritional status should be corrected as early as possible. Maintaining optimal rates of physical development may lead to significant cost savings. The results obtained may be used for future economic assessments and cost projections for the treatment of patients with pathology accompanied by poor nutritional status. Key words: cystic fibrosis, children, enteral nutrition, protein-energy malnutrition, malnutrition