Background: The aim of the present study was to investigate the relationship between maximum clot firmness (MCF) in rotational thromboelastometry (ROTEM®) and postoperative bleeding in patients on clopidogrel after emergency coronary artery bypass graft surgery (CABG). Methods: This observational study recruited 60 patients posted for emergency CABG following unsuccessful primary percutaneous coronary intervention (PCI) while on 600 mg of clopidogrel. The study population was divided into 2 groups on the basis of their MCF in the extrinsically activated thromboelastometric (EXTEM) component of the (preoperative) ROTEM® test: patients with MCF <50 mm (n = 16) and those with MCF ≥50 mm (n = 44). Postoperative chest tube drainage amount, need for blood product transfusion, postoperative complications, and duration of mechanical ventilation after CABG were recorded. Results: No significant differences were observed between the two groups regarding duration of surgery, cardiopulmonary bypass, and aortic cross-clamp time. Chest tube drainage at 6, 12, and 24 h after Intensive Care Unit admission were significantly higher in the patients with MCF below 50 mm. The need for blood product transfusion was higher in the group with MCF <50 mm. In patients who experienced postoperative bleeding of 1000 mL or more, the ROTEM® parameters of INTEM (Intrinsically activated thromboelastomery) α and MCF, EXTEM α and MCF, and HEPTEM (INTEM assay performed in the presence of heparinase) MCF (but not FIBTEM (Thromboelastometric assay for the fibrin part of the clot) values) were significantly lower than those with postoperative bleeding <1000 mL (P ≤ 0.05). Conclusions: When platelet aggregometry is not available, the ROTEM® test could be useful for the prediction of increased risk bleeding after emergency CABG in patients who have received a loading dose of clopidogrel.