Background: Elective coronary artery bypass grafting (CABG) is one of the most common heart surgeries performed recently. Among cardiac surgery patients, low preoperative left ventricular ejection fraction (LVEF) is common and has been associated with poor outcomes. Aim of Study: The aim of this study was to compare the postoperative outcome of coronary artery bypass grafting with low ejection fraction versus good ejection fraction. Patients and Methods: This research is a prospective, con-trolled randomized clinical trial involving 150 patients who are eligible for CABG. After appropriate consent from enrolled patients and local ethical committee, current study done on 50 consecutive adult patients with severe ischemic heart disease and low ejection fraction <40% (patient group) and 100 pa-tients with an EF >40% (control group), scheduled for elective Coronary Artery Bypass Grafting (CABG) as a study in Galaa Medical Compound for Armed Forces between April 2021 and March 2023. Results: There was significant prolonged cardiopulmo-nary bypass (CPB) time in low EF patient (153.95±36.73 min-utes) compared to normal EF patients (138.56±40.71 minutes) (p=0.026) with insignificant prolongation of aortic cross clamp (86.93+22.23 minutes) and total operative times (338.6±91.16 minutes) in patient group compared to (86.70±27.84 and 309.5±89.61 minutes) respectively in those with normal EF patients (p>0.05). Patients with low EF% (patient group) were statistically significant difficulty weaning from CPB compared to those with normal EF (control group) (p<0.001). Seven cases (16.7%) versus one (1.2%) weaned by IABP, ten cases (23.8%) versus one (1.2%) by combined support and two difficult (4.8%) weaning compared to no cases in patients and control groups re-spectively. The higher statistically significant levels of CK-MB (137.08 vs 90.75 U/L; p=0.000), prolonged ventilation times (35.60 vs 11.63 hours; p=0.000), ICU stays (3.72 vs 2.40 days; p=0.000) and hospital stays (12.65 vs 10.29 days; p=0.023) in patient group with low EF% compared to those with normal EF% respectively. Troponin I levels were statistically signifi-cant higher at induction (0.48 vs 0.23 ng/mL p=0.000), 2 hours (4.99 vs 3.94 ng/mL p=0.020), 12 hours (6.66 vs 5.25 ng/mL p=0.011), 24 hours (3.70 vs 2.84 ng/mL p=0.006) and 48 hours (1.73 vs 1.32 ng/mL p=0.006) postoperatively in patients with EF<40% compared to those with normal EF% (control group) respectively with a peak levels after 12 hours in both groups. Patients with low EF% (patient group) have statistically signifi-cant higher usage of IABP (40% intraoperative and 4% in ICU) compared to those with normal EF% (control group) (3% intra-operative and 3% in ICU) (p<0.001). Patients with low EF% (patient group) have statistically significant higher consuming postoperative inotropes (74%) compared to 31% in those with normal EF% (control group) (p=0.000). There was insignificant increased of mortality rate among patient group (8%) compared to control group (3%) (p=0.171). Conclusions: CABG in patients with EF <40% is frequent-ly associated with more complications than others with normal ejection fraction. In addition, cardiopulmonary bypass time and the use of IABP is also dependent on the preoperative ejection fraction. Patients with low EF% were difficulty weaning from CPB compared to those with normal EF.