Background. Postoperative delirium is a common complication after cardiac surgery, increasing mortality, duration and cost of treatment, impairing rehabilitation potential. Identifying the risk group for delirium can improve treatment outcomes due to increased alertness, early diagnosis and preventive measures. The aim of the study is to identify risk factors for the development of postoperative delirium in patients undergoing coronary artery bypass grafting (CABG). Material and methods. We analyzed 133 case histories of patients who underwent CABG in 2018 at the City Multifield Hospital in St. Petersburg. Inclusion criteria for the study: elective isolated coronary artery bypass grafting operations under general combined anesthesia, patients' age from 40 to 89 years, the absence of severe cognitive impairment, according to the results of the Self-Administrated Gerocognitive exam, chronic alcohol abuse and mental illness, no severe carotid atherosclerosis requiring surgery, Simpson ejection fraction > 30%. The presence of delirium was determined using the Nursing Delirium Screening scale. Results. Postoperative delirium developed in 23 (17%) patients. A statistically significant effect of age and the Charlson comorbidity index on the development of delirium was revealed. The odds ratio (OR) for age was 3.41 (95% confidencial interval (CI) 1.359-9.154, p = 0.01), for Charlson comorbidity index OR 4.92 (95% CI 1.93-12.95, p = 0.003) Conclusion. Age over 69 years and a Charlson comorbidity index of more than 5 points are significant predictors of the development of delirium in the postoperative period.