Purpose: The purpose of this study was to research the use of near-infrared spectroscopy (NIRS) on the neurocognitive functions in the patients undergoing coronary artery bypass grafting (CABG) with asymptomatic carotid artery disease.Methods: The study design was carried out with the participation of 79 patients in a prospective, randomized and double blind control method. The patients were separated into two groups as NIRS (n = 43) and no NIRS (n = 36). A neurocognitive test was applied preoperatively and postoperatively to all patients before discharge. Cognitive functions were evaluated by applying the Montreal Cognitive Assessment test (MoCA).Results: The decrease in the postoperative score of mean MoCA in no NIRS group was statistically significant when compared to preoperatively (p <0.001). Postoperative mean MoCA score was found to be significantly higher in NIRS group (NIRS: 26.8 ± 1.9 vs. no NIRS: 23.6 ± 2.5, p <0.001). It has been determined that there was a moderately positive significant correlation between the increase in the NIRS used patients (%) and increase in the MoCA score of the patients (r = 0.59, p <0.001).Conclusion: Intraoperative NIRS usage in the patients undergoing CABG with carotid artery disease might be useful due to its postoperative positive effects on the cognitive functions.