Objective: To test the hypothesis that levosimendan is more effective than intra-aortic balloon pump (IABP) support in cardiac surgical patients with low left ventricular ejection fraction to decrease cardiac troponin I levels (primary endpoint) and improve hemodynamics. Design: Prospective randomized trial. Setting: Tertiary cardiothoracic referral center. Participants: Ninety patients with coronary artery disease and left ventricular ejection fraction <35% who underwent surgery with cardiopulmonary bypass. Intervention: Patients were assigned randomly to 1 of 3 groups. Group A received a prophylactic IABP one day before surgery. Group B received a prophylactic IABP one day before surgery and a levosimendan infusion at a dose of 0.1 μg/kg/min with an initial bolus (12 μg/kg for 10 minutes) after anesthesia induction. Group C received a levosimendan infusion at a dose of 0.1 μg/kg/min with an initial bolus (12 μg/kg for 10 minutes) after anesthesia induction. Hemodynamic and biochemical data and rate of complications were analyzed. Measurements and Main Results: The cardiac troponin I level in group C 6 hours after surgery was lower than in group A (p = 0.048). The cardiac index in group A was significantly lower than in groups B and C. The intensive care unit stay was significantly shorter in group C than in groups A and B (p = 0.001). The need for inotropic support, the rate of complications, and mortality among groups did not differ. Conclusions: The infusion of levosimendan after anesthesia induction in cardiac surgical patients contributes to lower cardiac troponin I levels and improved hemodynamics compared with a preoperative IABP.