Background: The performance of coronary bypass surgery without cardiopulmonary bypass ("off pump") may reduce perioperative morbidity and costs, but it is uncertain whether the outcome is similar to that involving the use of cardiopulmonary bypass ("on pump"). In fact, the advantage of using off-pump myocardial revascularization is being documented in high risk subgroups. Objective: The purpose of this study was to compare on-pump versus off-pump myocardial revascularization in patients with multi-vessels disease. Patients and Methods: Sixty patients with multi-vessel disease requiring CABG surgery at a single institution were prospectively randomized to have the procedure performed with on pump(group A, n=30) or with off pump (group B, n=30). Different preoperative, operative, postoperative variables and six month follow up were evaluated among both groups. Results: There was no statistical difference between the two groups preoperatively regarding their age, sex, comorbidities (except emergency patients, which was significantly higher in group "B") and left ventricular function. Regarding intraoperative comparison, there was no significant difference in the total number of grafts. There was a significant difference in the intensive care parameters. The mechanical ventilation time was significantly shorter in group "B", and the blood transfusion required was significantly less in group "B". The ICU stay was significantly shorter in group "B".Left ventricular functions significantly decreased immediately and one week follow up postoperative, but backed up again after six months postoperative follow up in both groups. However, there was no statistically significant difference between both groups.The postoperative complications showed no statistically significant difference between both groups.The total hospital stay was significantly higher in group "A". Conclusions: Both on-pump and off-pump procedures usually result in excellent outcomes, but should be judged to choose the better from both techniques to every patient according to clinical condition of the patient, center equipment and surgeon experience.