Perioperative myocardial infarction is a potential consequence of coronary artery bypass surgery. The diagnosis is difficult due to multiple factors including postoperative chest discomfort, serum enzyme elevations and nonspecific electrocardiographic changes. No one test is reliable, but a combination of electrocardiogram, MBCK serum enzyme analysis and technetium pyrophosphate scanning should increase the probability of correct diagnosis. Using this method, the incidence of perioperative myocardial infarction in this study was six out of 100. Left ventricular function in the early postoperative period was adversely affected by perioperative myocardial infarction with a reduction in left ventricular ejection fraction (63 +/- 9% preoperative to 54 +/- 12% postoperative; P less than 0.05), whereas left ventricular ejection fraction was unchanged in the absence of perioperative myocardial infarction. The long term left ventricular function, however, appears to recover, and at two years after surgery there was no difference in rest or exercise left ventricular function between patients who suffered perioperative myocardial infarction versus those who did not. All patients with perioperative myocardial infarction survived to be discharged from hospital, and all returned for follow-up at two years. Their functional and work status was no different from those without perioperative myocardial infarction. This would suggest that, if patients survive a perioperative myocardial infarction, their long term functional status is no different from those patients without perioperative myocardial infarction.