Objective: The aim of this prospective randomized study was to compare the myocardial protective effects of sevoflurane and isoflurane during coronary bypass surgery. Methods: After induction of general anesthesia with etomidate 0.3 mg/kg, a bolus dose of pancuronium 0.1 mg/kg and remifentanil 1 mcg/kg was administered. For the maintenance of anesthesia, patients received either sevoflurane (n=20) at 2-4% or isoflurane (n=20) at 1-2%. Arterial blood samples were obtained as follows: before induction of anesthesia, after aortic unclamping, at postoperative period. Troponin-T, creatine kinase (CK), and creatine kinase-MB (CKMB) values were measured in all obtained samples. Statistical analysis was performed using two-way ANOVA analysis and Mann-Whitney test. Results: Heart rate was significantly higher in the sevoflurane group during the aortic side-clamp period, at the 10th minute and 20th minute after cardiopulmonary bypass (CPB) ending. The CK-MB values at 24th postoperative hour in the sevoflurane group were found to be significantly lower from the isoflurane group. The troponin-T values following the removal of the cross-clamp (1.015 (0.935-1.850) ng/ml vs 1.469 (1.290-1.645) ng/ml, p<0.001) and those at the 24th postoperative hour (5.345±0.654 ng/ml vs 8.715±1.020 ng/ml, p<0.001) were significantly lower in the sevoflurane group when compared to those in the isoflurane group. Conclusion: Sevoflurane provides a better myocardial protection than isoflurane, as may be inferred by the lower levels of the myocardial injury markers troponin-T and CK-MB observed with sevoflurane.