Objectives: We aimed to evaluate the potential effects of heart positioning during off-pump CABG (OPCAB) without a cardiac stabilizer device on serum levels of ischemia modified albumin (IMA) and cardiac output (CO). Materials and Methods: This was a prospective study in which consecutive patients who underwent isolated OPCAB were included. Data including electrocardiography and intraarterial hemodynamic monitoring parameters were recorded. Arterial pressure waveform was analyzed. CO was measured for circumflex coronary artery (Cx), diagonal coronary artery (D1), left anterior descending coronary artery (LAD), and right coronary artery (RCA) positions. Preoperative and postoperative 1st, 2nd, 4th, and 12th-hour blood samples were taken for serum ischemia modified albumin measurements.Results: Forty patients who underwent OPCAB were included in the study. The mean age was 60.3±10.2 years. Hospital mortality, stroke, postoperative myocardial infarction, acute kidney injury, sternal infection, and re-operation for bleeding/tamponade were not observed postoperatively. Six patients (15%) who developed postoperative atrial fibrillation (AF) had a significantly higher mean serum IMA level compared with patients who did not. There was no statistically significant difference in preoperative and postoperative mean serum IMA levels (p=0.925). Mean CO values measured at four different heart positions were not significantly different from each other except for a difference between LAD and Cx (p=0.002). Conclusion: Our results showed that when the heart was in the Cx anastomosis position, the CO was significantly lower than the LAD position; however, there was no significant serum IMA raise despite CO decrease. IMA levels did not change significantly from baseline values. Patients who developed postoperative AF had higher IMA levels than patients who did not develop AF