Aim: Monocyte/high-density lipoprotein (HDL) ratio (MHR) is an inflammatory marker associated with vascular diseases. The aim of this study is to evaluate the MHR in patients with symptomatic carotid artery stenosis and to examine its relationship with the degree of stenosis. Methods: The study was conducted as a case-control study, with data obtained from patients’ files between January 2020 and May 2021. Ninety patients with symptomatic carotid stenosis and 40 healthy controls were included in the study. For vascular imaging, computed tomography angiography and/or digital subtraction angiography were used. Carotid artery stenosis was grouped according to North American Symptomatic Carotid Endarterectomy Trial criteria. Tests for monocyte and HDL cholesterol were performed, and the MHR was calcu-lated. Results: There were 67 male and 23 female patients with a mean age of 65.10±12.26 years in the study. In 46 (51.1%) of the patients, there was 50% or more carotid artery stenosis. The HDL cholesterol level was lower, and the MHR was higher in the patient group (p=0.042, p=0.041, respectively). Monocyte and MHR levels were higher in patients with 50% or more carotid stenosis (p=0.04). Conclusion: The MHR is a predictive biomarker for the degree of symptomatic stenosis in the carotid artery.