The incidence of postoperative delirium following coronary artery bypass surgery was 28 percent. This rate is comparable to that after open-heart surgery. However, of those variables which were previously found to correlate with delirium in the open-heart group, only severity of postoperative illness in the recovery room significantly correlated with delirium in patients having bypass. The relationship between personality type and delirium, previously found to be significant, was suggestively associated in these patients. A history of myocardial infarction prior to surgery was significantly associated with delirium.