A significant number of patients exhibit impairment in cognitive function immediately following surgery or later; the impact of this postoperative cognitive dysfunction on the recovery and quality of life of the patient but also on the necessity for supportive and rehabilitation care is important. Risk factors for postoperative cognitive impairment and postoperative delirium have been described and it is these groups of patients that require early identification and careful follow up to avoid complications in postoperative care. Central nervous system complications continue to be major causes of morbidity and mortality especially after cardiac surgery, and there is a growing interest in literature in the evaluation of the effects of on pump and off pump coronary artery bypass grafting surgery on postoperative cognitive impairment. Despite several recent attempts, no gold standard treatment has been devised for postoperative cognitive impairment; however, the potential beneficial role of some pharmacological agents is currently examined. There is also fascinating research evolving with regard to the pathophysiologic mechanisms of cognitive dysfunction; it seems possible that the central nervous system responsiveness to systemic inflammatory mediators augments injury from perioperative neurological insults.