Abstract: AIM:To evaluate the effect of milrinone on patients with ventricular dysfunction undergoing coronary artery bypass graft (CABG). METHODS: Sixty-two patients with impaired left ventricular function ［left ventricular ejection fraction (LVEF)<35%］ undergoing CABG were enrolled. Patients were randomized to receive either an intraoperative bolus of milrinone (50 μg/kg) or saline as placebo, followed by a 24-h infusion of each agent ［0.5 μg/(kg·min)］. Hemodynamic parameters and transthoracic echocardiographic measurement of systolic and diastolic functions were evaluated. RESULTS: Serum levels of creatine phosphokinase (CPK), MB isoenzyme of creatine kinase (CK-MB), occurrence of myocardial ischemia or infarction, and mean duration of using inotropic agents were significantly lower in the milrinone group (P<0.05, P<0.01). There were no significant differences between groups in the development of ventricular arrhythmia, intra-aortic balloon pump and inotropic support requirement, duration of mechanical ventilation and 24-h mortality rate. Although mean preoperative LVEF was significantly lower in milrinone group, there was no significant difference in postoperative LVEFs. CONCLUSION: We suggest perioperative administration of milrinone in patients undergoing CABG, especially in those with low LVEF.