Annotation. Pulmonary complications are a key problem in the postoperative period in patients with diseases of the thoracic cavity. They are characterized as the main factors of longer recovery and hospital mortality. The aim of the study was to compare the indicators of oxygenation of patients and the number of postoperative pulmonary complications after thoracic surgery, depending on the method used to select a dual endobronchial tube. The study was performed on 192 patients with diseases of the thoracic cavity (esophagus, lungs, mediastinum), operated on in the thoracoabdominal department of the Shalimov National Institute of Surgery and Tranplantology. A retrospective comparison group – 96 patients after thoracic surgery, which used the choice of DLT size according to the well-known method of Slinger “according to the patient's height”. The study group consisted of 96 patients after thoracic surgery, in which the choice of the size of the dual endobronchial tube was used according to the developed method (according to the formula that evaluates morphometric indicators of height, sex and diameter of the left main bronchus). EZR v 1.54 statistical software was used for statistical calculations. (graphical user interface for statistical software R version 4.0.3, R Foundation for Statistical Computing, Vienna, Austria). Pulmonary complications developed in 33 (34.4%) patients of the control group and in 13 (13.5%) patients of the study group, the difference was statistically significant, p=0.001. One-factor analysis revealed a link between the risk of complications and the indicators method, sex, PaCO2, PaO2. For the study group, the risk of complications is lower (p=0.001), BP=0.30 (95% CI 0.15-0.61) compared with the control group. The risk of complications for men is higher (p=0.048), BP=2.33 (95% CI 1.01–5.37) compared to women. An increase in the risk of complications with an increase in PaCO2 (p<0.001), BP=1.34 (95% CI 1.21-1.49) with an increase in the indicator by 1 unit, respectively. With increasing PaO2, the risk of complications decreases (p<0.001): BP=0.96 (95% CI 0.94-0.98) – with increasing 1 unit. Thus, the application of the proposed method in comparison with the traditional method reduces (p=0.001) the number of postoperative pulmonary complications by 2.5 times (from 34.4% to 13.5%).