Carotid duplex ultrasonography is a noninvasive and economical method used to diagnose and monitor carotid artery diseases. However, the accuracy of carotid duplex ultrasonography is decreased in the presence of contralateral high-grade stenosis or occlusion. Among the criteria for evaluating the degree of carotid artery stenosis, the Society of Radiologists in Ultrasound consensus criteria are the most widely used owing to their high sensitivity and specificity. Here, we have presented a case in which internal carotid artery (ICA) stenosis was overestimated using the consensus criteria due to the chronic occlusion of the contralateral ICA.