The objective was to evaluate the possibility of determining the risk of postoperative complications and death in patients with peripheral lung cancer based on absolute (V’O2peak) and relative (V’O2peak % from the proper) values of the oxygen consumption index at the peak of physical activity. Materials and methods. 128 patients with peripheral lung cancer (68±8 years old) who underwent surgery at the Pavlov University Clinic in 2018–2023 were studied. All patients underwent cardiopulmonary exercise testing (CPET) 3–7 days before surgery. V’O2peak was recorded at the maximum load level, calculated based on the method of moving averages of 5 out of 7, V’O2peak% from the proper – based on a linear relationship by age and gender. For the analysis, the patients were divided into groups depending on the presence of postoperative complications and the outcome of hospitalization (discharge or death). For statistical processing of data, the following were used: Student’s t-test, Mann – Whitney U-test, Pearson’s chi-square test, Fisher’s exact test. Results. When comparing the group of patients with and without complications, it was not possible to identify differences in the V’O2peak index (p = 0.972). The probability of complications in patients with V’O2peak > 15 ml/min/kg was 1.065 times lower than in the group with V’O2peak < 15 ml/min/kg, the differences were not significant (OR = 0.939; 95% CI: 0.410 – 2.152). When comparing V’O2peak in groups of patients with fatal outcome and discharged patients, no differences were found (p = 0.387). When comparing the group of patients with complications with the group without them, there were no differences in V’O2 peak % predicted value. There were also no significant differences when comparing the group of patients with fatal outcome with the group of discharged patients (p = 0.735). Conclusions. The results obtained indicate that the absolute and relative values of oxygen consumption at the peak exercise (V’O2peak) are not reliable predictors of the risk of postoperative complications or death in operated patients with peripheral lung cancer.