Objective. To analyze the structure and severity of early postoperative cognitive dysfunction as well the accompanying spectral electroencephalographic (EEG) changes in patients underwent coronary artery bypass grafting (CABG) depending on the presence or absence of small and moderate internal carotid stenosis. Material and methods. Fifty seven patients, aged from 45 to 70 years, were stratified into two groups: without stenosis (n=35, mean age 54.3±6.4 years) and with internal carotid stenosis (n=22, mean age of 57.5±5.8 years). For all patients planned on-pump CABG was performed. Results. The frequency and severity of cognitive deficits in the postoperative period were higher in patients with internal carotid stenosis compared to patients without stenosis. Also, the patients with stenosis had more pronounced EEG signs of cortical dysfunction and brain damage after CABG compared to patients without stenosis. Conclusion. The presence of carotid >50% stenosis increases the severity of cognitive deficits and brain damage in patients underwent on-pump CABG.