Cerebral injury is a frequent complication of cardiac surgery, and it has been associated with high mortality, morbidity, hospital costs; an increased likelihood of admission to a secondary care facility after hospital discharge; and impaired quality of life. This article examines postulated mechanisms for cerebral injury from cardiac surgery. Most emphasis has been placed in the past on the intraoperative interval as being the period of highest cerebral vulnerability. Many clinical cerebral events, however, occur in the postoperative period.