Background: Patients with ischemic heart disease and reduced ejection fraction have increased risk for postoperative complications and mortality. Our aim was to evaluate the effect of low EF (<40%) on the early outcomes after CABG and identify the predictors of mortality. Methods: From August 2018 to November 2019, 170 consecutive patients underwent CABG. Group 1 included 120 patients with EF (<40%; 37.49 ± 2.89%); 94 were men (78.3%), and the mean age was 55.83 ± 8.04 years. Group 2 included fifty patients having EF (>40; 57.90% ± 2.27%), 41 were men (82.0%), and the mean age was 54.30 ± 7.01 years and used as a control group. Results: Overall 30-day mortality was 10/120 patients (8.3%). Factors associated with higher mortality were females (70.0% vs. 17.3%, P < 0.001); older age (61.40 ± 7.01 vs. 55.32 ± 7.97 years, P = 0.025); diabetes mellitus (100% vs. 51.8%; P = 0.003); longer cardiopulmonary bypass time (148.70 ± 40.12 vs. 108.49 ± 36.89 min; P = 0.012); longer cross clamp time (88.19 ± 31.94 vs. 64.77 ± 22.67 min; P = 0.049), longer total operative time (6.82 ± 1.03 vs 5.38 ± 0.95 hours; P = 0.001); intra-aortic balloon pump (IABP) insertion (90.0% vs. 10.9%; P < 0.001); intra-operative complications (60% vs. 1.8%, P < 0.001); ventricular tachycardia and ventricular fibrillation (30% and 50% vs. 4.5% and 5.5% respectively; P = 0.002 for both); myocardial infarction (70% vs 11.8%, P < 0.001), and lower postoperative ejection fraction (21.46 ± 1.93 vs 40.30 ± 8.19%, P < 0.001). In patients with low EF, postoperative NYHA and CCS angina class have improved compared to the preoperative levels (1.50 ± 0.61 vs. 3.31 ± 0.56; P < 0.001 and 1.38 ± 0.52 vs. 3.11 ± 0.55; P < 0.001 respectively). Conclusion: CABG in EF < 40% is associated with more complications compared with those had EF higher than 40%; however, the clinical and echocardiographic parameters improved over time.