Aim. Encephalopathy after cardiac surgery is severe complication. It was performed retrospective analysis to estimate causes of postoperative encephalopathy and its relation to other complications. Material and methods. Treatment of 152 patients with heart valve diseases was analyzed. Encephalopathy occurred in 13 (8.5%) patients who were included into study group, control group consisted of patients without encephalopathy. Results. It was revealed that patients in group 1 had lower values of FEV1 (71.5±31.5% vs. 89.9±17.1%), maximal expiratory flow 75 (41.6±25.7% vs. 56.8±26.6%) and maximal expiratory flow 50 (54.1±27.2% vs. 77.2±31.1%). Also there was higher pulmonary pressure (54.0±17.1mm Hg vs. 46.2±20.3 mm Hg) and larger RA volume (117.0±62.6 ml vs. 70.6±30.1 ml). There were longer duration of CPB (169.2±80.3 min vs. 118.9±47.3 min), greater blood loss (1103±822 ml vs. 685±298 ml) and intraoperative concentration of glucose and lactate in group 1. In the study group there were high need for vasopressor support (61.5% vs. 7.3%), incidence of respiratory failure (84.6% vs. 5.8%) and mortality rate (53.8% vs. 0.7%). Conclusions. Modifiable (preoperative pulmonary function, duration of CPB and blood loss) and non-modifiable (pulmonary pressure, preoperative RA volume) factors contribute to encephalopathy occurrence. Postoperative encephalopathy is associated with increased need for vasopressor support and incidence of respiratory failure. Mortality rate is statistically significantly higher in patients with encephalopathy than in those without it.