Purpose: To evaluate the routine use of pulmonary artery catheters (PAC) in patients who undergo aortic surgery. Methods: One hundred twenty patients were randomized to placement of PACs for perioperative monitoring and hemodynamic optimization (tune up) in the intensive care unit on the night before aortic operation, or to intravenous hydration in the ward and perioperative monitoring without PACs. Before randomization, all patients underwent routine adenosine thallium-201 scintigraphy. Results: To meet predetermined endpoints, 30 PAC patients (50%) received nitrates, inotropic agents, or both. PAC patients received more fluid in the preoperative period (p < 0.001) and in the first 24 hours after operation (p = 0.002) than control subjects. Eleven PAC patients (18%) and three control subjects (5%) had adverse intraoperative events (p = 0.02). There were 20 adverse postoperative events in 15 PAC patients (25%; nine cardiac, seven pulmonary, four acute tubular necrosis), which was not different compared with 11 postoperative events in 10 control subjects (17%; five cardiac, five pulmonary, one acute tubular necrosis). There were also no differences in duration of mechanical ventilation, intensive care unit stay, or hospital stay between groups. Postoperative cardiac complications were more common among patients who had a history of congestive heart failure (p = 0.02; odds ratio, 3.75; confidence interval, 1.3 to 11) or reperfusion defects on adenosine thallium scintigraphy (p = 0.01; odds ratio, 3.4; confidence interval, 1.2 to 9.4), regardless of group. Conclusions: Routine use of PACs for perioperative monitoring with the above protocol during aortic surgery is not beneficial and may be associated with a higher rate of intraoperative complications. Preoperative tune up does not prevent postoperative cardiac, renal, and other complications. Variables such as cardiac risk factors and adenosine thallium scintigraphy may be more important predictors of cardiac events in patients who undergo aortic operations.