Background: During coronary artery bypass grafting (CABG), the myocardium is subjected to endure periods of ischemia and reperfusion, which may result in post-ischemic contractile dysfunction. That is a major contributor to early and late morbidity and mortality and increased requirement of pharmacologic and mechanical circulatory support.Glucose insulin potassium (GIK) infusion was thought to provide a cardioprotective effect. Objective: To investigate whether the use of GIK solution in patients undergoing on-pump CABG affects requirements of inotropes. Patients and Method: In this prospective, randomized placebo-controlled trial, 64 patients were assigned into two groups: the GIK group in which glucose-insulin and potassium infusion was given during CABG surgery, and the non-GIK group in which only saline infusion was given during the procedure. Results: In the GIK group, all patient needed not more than two inotropes with mean of 1.28 ± 0.46, while in the non-GIK group there were patients who need up to three inotropes with mean of 1.56 ± 0.56 (P. value of 0.032). Conclusion: GIK infusion during on-pump CABG reduces perioperative inotropic requirements.