Cardiac disease continues to be the leading cause of morbidity and mortality following peripheral vascular surgical procedures. Although the mechanism of sudden myocardial infarction remains elusive, many possibilities exist. The role of catecholamines is intriguing in view of the evidence that beta-adrenergic blockers reduce cardiac morbidity and mortality in vascular surgical patients. To ascertain whether the plasma catecholamine levels rise significantly during abdominal aortic aneurysm repair, serial determinations of plasma epinephrine and norepinephrine levels were performed in 18 patients. Epinephrine levels rose significantly from preoperative baseline values both during the operation and postoperatively, and norepinephrine levels rose significantly at 24 hours postoperatively. Although only one patient studied developed a myocardial infarction, the finding that patients undergoing aortic surgery uniformly experienced abnormally high serum catecholamine levels supports other evidence that perioperative myocardial ischemic events have a hormonal component.