Background: Patients with poor left ventricular function undergoing cardiac surgery frequently require inotropic drug support immediately after cardiopulmonary bypass. Levosimendan is an effective agent that acts via two complementary mechanisms. It enhances cardiac contractility and reduces cardiac workload. Aim: to assess the effect of histidine-tryptophan-ketoglutarate cardioplegia (HTK cardioplegia) alone or combined with preoperative infusion of levosimendan on the vasoactive inotropic score in patients with poor left ventricular function undergoing coronary artery bypass grafting. Material and method: this double-blinded randomized controlled trial was carried on 100 patients, divided into two groups; Levosimendan group ( = 49): patients received 0.1ug/kg/min levosimendan without loading, 12 hours preoperatively and continued for a total of 24 hours. Control group ( = 51): patients received a placebo 12 hours before surgery and continued for a total 24 hours. Both groups received HTK cardioplegia after cross-clamping of the aorta approximately 20 ml/kg into the ascending aorta over 6–8 minutes at a temperature of 4−10°C. Results: Levosimendan group was superior to control group with statistical significance regarding the need of intraaortic balloon pump (IABP), vasoactive inotropic score over the first 24 hours, troponin levels over the first 72 hours, ICU stays, hospital stay, and cumulative hospital costs. Although the incidence of postoperative low Cardiac output syndrome (LCOS), atrial fibrillation (AF), acute kidney injury (AKI), and overall mortality was lower in levosimendan group, but all were not statistically significant. Conclusion: Preoperative infusion of levosimendan combined with HTK cardioplegia in patients with poor cardiac function decreased vasoactive inotropic score and lowered the costs of hospital stay.