Objective: The aim of this study was to determine whether serum levels of intestinal type fatty acid binding protein (I-FABP) are related to intestinal ischemia in patients undergoing coronary bypass surgery. Methods: The study was planned as prospective, observational. Elective coronary artery bypass candidate patients between ages of 50 and 70 were consecutively included in the study. Thirty-five patients scheduled for cardiopulmonary bypass (CPB) were identified as the CPB group and 16 patients not scheduled for CPB were identified as the off-pump coronary artery bypass surgery (OPCAB) group. The variables between and within the groups were analyzed with Student’s t, Mann-Whitney U, Friedman and Wilcoxon tests respectively. Results: In both CPB and OPCAB groups, I-FABP level at the end of the operation was significantly higher than that noted at the beginning of the operation (p<0.005). In the CPB group, there was a significant drop in I-FABP from the end of the operation to each of the postoperative time points (12th hour and 24th hour) (respectively p<0.001, p<0.001). In the OPCAB group, the I-FABP levels at both postoperative time points were lower than that at the end of the operation (p<0.001), and the level at 24-hour post-surgery was significantly lower than at both the end-of-operation I-FABP value (p<0.001) and the 12-hour post-surgery I-FABP value. Conclusion: Since we have not observed any intestinal ischemia through our research, slight changes of I-FABP measurements make us believe that I-FABP would be a valuable way to monitor for intestinal ischemia in patients who undergo cardiac surgery.