Nutritional deficiency very often occurs in the patients having upper digestive tract surgical diseases, both malignant and of benign nature; its severity increases during hospitalization under the influence of the surgical intervention or the «specialized» treatment. About 50% of the surgical patients are known to be malnourished, 60—80% of those presenting with esophageal and gastric cancer have cachexia, whereas 70—80% of the malnourished patients are not at all identified as such, and no action is taken to treat their nutritional deficit. The on-going protocols of the perioperative care for the patients selected for the surgical intervention on the organs of the upper gastrointestinal tract envisage routine screening for the identification of the patients at risk of malnutrition in the preoperative period, nutritional support, avoidance of prolonged fasting during major surgery on the upper digestive tract, and early enteral nutrition during the postoperative period with the active correction of all possible causes for malnutrition. The objective of the present study was to investigate the nutritional status of the patients scheduled for major esophageal and gastric surgery and to elucidate the correlation between the risk of malnutrition, perioperative nutritional support, and clinical outcomes. Material and methods. The study group included 54 consecutive patients with benign and malignant diseases of esophagus and stomach admitted to the esophageal and gastric surgery department of B.V. Petrovsky Research Centre of Surgery for major surgical procedures in combination with perioperative care protocol throughout the period from 2014 to 2016. The nutritional screening during the perioperative period included the calculation of BMI before and after surgery with the use of the Nutritional Risk Screening 2002 (NRS-2002) tool to identify patients at risk of developing nutritional deficiency as well as the laboratory analyses, such as the measurement of the serum albumin, prealbumin, transferrin, iron, and haemoglobin levels. The clinically meaningful end-points chosen for the present study were the total length of stay in the hospital (LOS), the length of stay in the intensive care unit (ICU), and morbidity. Results. The use of the NRS-2002 tool to identify malnutrition made it possible to demonstrate that 66,7% of the patients belonged to the high-risk group (more than 3 points) and needed the special nutritional support during the preoperative period even though weight deficit (BMI lower than 18,5 kg/m2) was documented only in 25,9% of them. All the patients suffered the loss of weight during the hospitalization period despite the nutritional support (average weight loss was 4,3±3,6 kg); the weight decreased most dramatically in the patients having higher BMI. There was no statistical difference between the high and the low-risk groups as regards the total hospital LOS, ICU LOS, and the frequency of complications depending on BMI and malnutrition risk group affiliation. The mortality rate was 0%. Conclusion. About 70% of the patient presenting with upper digestive tract surgical diseases and hospitalized for the pre-planned surgical intervention on the stomach and oesophagus are at high risk of development of nutritional deficiency and in need of special nutritional support during the perioperative period.