Objective: To investigate the perioperative and postoperative effects of preoperative levosimendan use in coronary artery patients with low ejection fraction (EF) (<40%). Material and Methods: A total of 6,571 coronary bypass patients who were treated at Kartal Koşuyolu High Specialization Training and Research Hospital between 2016 and 2019 were scanned, and 132 patients with preoperative EF below 40% were retrospectively analyzed. The patients were divided into 2 groups as those who received preoperative levosimendan (Group 1: 90 patients) and the control group, who did not receive it at all (Group 2: 42 patients). All of the patients included in the study were onpump coronary bypass patients and excluded off-pump bypass, emergency bypass, and other concomitant procedures. Results: In terms of EF values, improvements over time were significantly different in favor of Group 1 (p<0.043). The duration of the intensive care unit stay in Group 1 was longer (p<0.047). The changes in patients in terms of postoperative venous oxygen saturation over time were found to be statistically positive in favor of Group 1 (p<0.042). Mortality was observed in 5 patients in the postoperative early period (first 30 days), all of whom were from Group 1. However, no statistical difference was observed. Conclusion: Preoperative use of levosimendan in coronary artery patients with low EF improved some hemodynamic parameters; however, it did not make a significant hemodynamic and clinical contribution to surgery success in high-risk patients.