Background: Cognitive impairment is common complication after cardiac surgery. It complicates not only patient’s recovery, return to the normal rhythm of life, but also has a negative impact on quality of life. Objective: the aim of this study was to investigate the cognitive impairment`s prevalence and impact of quality of life for the patients after cardiac surgery. Results: Before cardiac surgery mild cognitive impairment was determined to 20,8 percent, moderate – 3,3 percent. After surgery almost double increased mild cognitive impairment – 46,1 percent, moderate – 4,9 percent. Older age, lower education, smoking and prolonged hospitalization before surgery has an impact on cognitive impairment. Postoperative cognitive impairment are influenced by older age, prolonged hospitalization before surgery, prolonged operation, mechanical ventilation and duration of cardiopulmonary bypass. For patients without cognitive impairment before cardiac surgery general health assessment improved the most, vitality/viability reduced. For patients with cognitive impairment significantly improved physical activity and pain sens, and general health assessment has improved slightly. Conclusions: Preoperative cognitive impairment determined to 1/4 patients. Mild cognitive impairment after surgery was slightly increased. Older age, lower education and prolonged hospitalization before surgery, have an impact of cognitive impairment before and after surgery. Not depending on cognitive impairment for all patients improved general health assessment, and reduced vitality/viability.