In spite of the progress in medicine post operative cognitive deficiency (POCD) remains an important clinical problem. Since the introduction of cardiac surgery there have been frequent reports of its adverse neurological outcomes. Recent technological advances have contributed to a lesser occurrence of clinically evident complications such as coma, stroke, epilepsy or blindness. This brought to attention a more common yet occult disorder-POCD. The above malady mostly concerns memory and executive functions. POCD has a negative impact on the quality of life and labor market attachment, however it's relation to mortality seems to be most disturbing. Prevalence of POCD is mainly associated with microembolisms, hipoperfusion and inflammatory reaction of the central nervous system following cardiac surgery. In addition many studies have shown the importance of biochemical disorders, cerebral oedema and the influence of comorbidities in the development of POCD. In the light of available evidence, there is no substantial difference between the cognitive outcomes of various types of cardiac surgery. Recent studies show that POCD in this clinical setting is mostly mild and transient. There are, however, patients who suffer from persisting POCD. Modern medicine has not developed standards for treatment of this complication. Setting up methods for prevention, detection and treatment of POCD should be the concern of both physicians and researchers in the following years.