Aim. To analyze risk factors for postoperative cognitive dysfunction in cardiac patients. Material and methods. A total of 22 patients (16 men and 6 women) aged 62±0.7 years were examined. Mean NYHA functional class was 3.4±0.3. CPB surgery was performed (CPB time — 90±1.6 minutes, myocardial ischemia time — 62±1.3 minutes). In 81.8% of patients coronary artery bypass grafting (CABG) of 3.2±0.2 arteries was made, heart valve replacement — in 4.6% and combined surgery in 13.6%. Results. We evaluated the significance of early encephalopathy that manifests at the stage of patient waking after surgery and requires additional sedation. Preoperative and intraoperative clinical and laboratory predictors of postoperative encephalopathy were determined. We proved deterioration of electroencephalographic parameters and the results of neurocognitive testing in patients with early encephalopathy. Perioperative dynamics of inflammatory cytokines and markers of neuronal damage was defined. Conclusion. S-100 protein is the most informative neuronal marker. Cerebral complications are associated with significantly increased S-100 level compared with uncomplicated patients.