Coronary artery bypass graft surgery, with current operative mortality rates of one to three percent, is now an accepted treatment for coronary artery disease. However, perioperative myocardial infarction (PMI) is not a rare complication of this procedure, and the precise mechanism of its occurrence is not well elucidated. We experienced a case of 70-year-old man who had transmural hemorrhagic PMI in the distribution of the grafted vessel and died due to low output syndrome in spite of vigorous treatment. All five grafts were found to be well patent at autopsy. In this case, the cause of PMI was supposed to be inadequate intraoperative myocardial protection and reperfusion injury.