Background and Objectives Metabolic syndrome is a medical problem featured by the coexistence of several risk factors such as, heart disease, stroke, and diabetes. The association between metabolic syndrome and incidental paranasal sinusitis has not been definitely proved yet. This study was established to prove if metabolic syndrome might be related to incidental paranasal sinusitis.Subjects and Method Of 5682 patients who had undergone brain MRI for regular checkups between 2011 and 2018 at Kangbuk Samsung Health Care Center, we analyzed 2882 cases with normal sinus and incidental paranasal sinusitis that had been deciphered by specialized radiologists. Data of various components of metabolic syndrome were also used. Multivariable logistic regression analysis was performed to calculate the odds ratio (OR) of having incidental paranasal sinusitis between subjects with metabolic syndrome components and those without.Results Of 2882 patients aged over 18 years (mean age, 51.8±9.47 years; 55.4% male), 353 incidental paranasal sinusitis subjects (232 male with mean age of 51.39±9.27 years and 121 female with mean age of 52.43±9.69 years) were identified. Metabolic syndrome was identified in 554 patients. The adjusted OR of having incidental paranasal sinusitis was 3.03 (95% confidence interval [CI]: 1.58-5.83) in female with metabolic syndrome. In female, the adjusted OR of having incidental paranasal sinusitis was 2.10 (95% CI: 1.20-3.67) in those with low high density lipoprotein (HDL) cholesterol (<50 mg/dL) and 1.83 (95% CI: 1.06-3.16) in those with higher body mass index (BMI) (≥25 kg/m²).Conclusion Results of this study suggest that female with metabolic syndrome, low HDL cholesterol, and high BMI have higher risks for incidental paranasal sinusitis.