Background. Fragmented QRS complex (fQRS) is associated with increased morbidity and mortality, sudden cardiac death and recurrent cardiovascular events. However, its prognostic role has not been studied comprehensively in patients undergoing coronary artery bypass graft (CABG) surgery. In this study, we investigated the relationship between the presence of fQRS, and the prognostic markers and in-hospital major adverse cardiovascular events (MACE). Methods. Two hundred and forty two eligible patients who underwent CABG surgery at our institution were enrolled consecutively. In analysis of fragmentations on electrocardiograms, presence of fQRS was defined as various RSR' patterns (>= 1 R' or notching of S wave or R wave) with or without Q waves without a typical bundle-branch block in two contiguous leads corresponding to a major coronary artery territory. MACE was defined as cardiac death, recurrent myocardial infarction, heart failure, cerebrovascular event, sustained ventricular tachycardia or fibrillation. Results. Patients with fragmented QRS had older age (64 +/- 10 vs. 61 +/- 9 years, p = 0.03), prolonged QRS time (99 +/- 11 vs. 87 +/- 11 ms, p < 0.001), higher rate of Q wave on ECG (29% vs. 12%, p = 0.001), higher European system for cardiac operative risk evaluation (EUROSCORE) (4.0 +/- 1.9 vs. 2.6 +/- 1.6, p < 0.001) and lower left ventricular ejection fraction (LVEF)% (43 +/- 12 vs. 60 +/- 12, p < 0.001) in comparison to patients with non-fragmented QRS. In addition, the patients with fQRS had longer cross-clamp time (67 +/- 23 vs. 55 +/- 20 minutes, p < 0.001) and extracorporeal circulation (105 +/- 31 vs. 91 +/- 30 minutes, p < 0.003), increased inotropic usage (p < 0.001) and prolonged cardiac surgery intensive care unit (53 +/- 25 vs. 35 +/- 12 hours, p < 0.001) and in-hospital stay after CABG. Conclusion. FQRS may have additional value in the assessment of cardiac function and in prediction of intra-and post-operative hemodynamic instability and adverse cardiovascular events. Fragmentations on admission ECG may be useful for identifying patients with higher risk who will need additional support after CABG surgery.