Improvements in cardiac surgery mortality and morbidity over the years have focussed interest on the neurologic injury that may accompany an otherwise successful operation.The spectrum of brain injury following cardiac surgery ranges from neurologic death (0.21-2.0%), stroke (1.1-6.6%), and peri-operative encephalopathy.Cognitive impairment is a more frequent complication and is found in a significant proportion of patients after cardiac surgery.Patients with complex surgery and earlier post-operative cognitive testing are more likely to show new deficits.