Aim: to evaluate the efficacy of metabolic disorders perioperative correction and the completeness of providing macronutrients in cancer patients when standard and specialized sterilized mixtures for enteral nutrition are included in the nutritional support program. Patients and Methods: the analysis of the enteral nutrition clinical efficacy during the perioperative period in cancer patients using Nutrien line liquid sterilized mixtures was carried out. The treatment results of 89 patients with GIT neoplasms who were treated in the surgical department and ICU of the Main Military Clinical Hospital named after N.N. Burdenko and the F.I. Inozemtsev City Clinical Hospital were analyzed. Personalized metabolic and nutritional support was provided before and after surgery. The effectiveness of metabolic disorders correction after surgery was evaluated on the basis of specialized examination methods. Results: after preoperative nutritional support, there was a significant increase (average group values) in total protein — 67.3±1.2 g/L, albumin — 33.5±2.3 g/L, transferrin — 1.5±0.11 g/L (p<0.05), and the absolute WBC count — 969±39 109/L (p≤0.05). Group 2 showed a decrease in the number of patients with grade 2 nutritional deficiency (by 8.3±1.71%, p<0.05); group 3 — the number of patients with positive dynamics of nutritional deficiency resolution was less (by 4.5±1.1%, p<0.05). In the postoperative period, in patients with diabetes mellitus, respiratory insufficiency, purulent-septic complications, who required personalized nutritional therapy with specialized mixtures, normalization of metabolic parameters was achieved by the 7–10 days of the postoperative period, which was confirmed by normalization of biochemical parameters and a decrease in nutritive demand. Conclusion: the study results on the use of enteral nutrition mixtures in the complex of perioperative nutritional support in cancer patients showed high clinical efficacy and provided the possibility of choosing a mixture based on a specific clinical situation, taking into account a personalized nutritional support program. KEYWORDS: nutritional support, pharmaconutrients, enteral nutrition, liquid mixtures. FOR CITATION: Arykan N.G., Evdokimov E.A., Stets V.V. et al. Enteral nutrition in perioperative nutritional support and rehabilitation during surgical treatment of oncological diseases. Russian Medical Inquiry. 2021;5(3):138–144. DOI: 10.32364/2587-6821-2021-5-3-138-144.