The etiology and incidence of neurologic injury occurring after cardiac operations employing cardiopulmonary bypass is reviewed. Results of studies demonstrating the role of microemboli generated by pump oxygenators, and evidence for the efficacy of arterial line filtration to decrease delivery of emboli into the cerebral circulation and to decrease postoperative neuropsychological dysfunction, are similarly reviewed. The impact of different strategies for management of pH during moderate hypothermic cardiopulmonary bypass on cerebral blood flow and coupling of cerebral flow and metabolism, as well as their impact on the incidence of postoperative cognitive dysfunction, are also discussed, along with the results of studies examining the efficacy of various agents including thiopental, nimodipine, and nafamostat to decrease cognitive dysfunction subsequent to bypass.