Metabolic syndrome (MS) is associated with chronic kidney disease (CKD). The objective of this study is to examine the association between obesity and MS-related CKD in nondiabetic, nonhypertensive Korean adults. Korea National Health and Nutrition Examination Survey III data from 3771 nondiabetic, nonhypertensive Koreans were analyzed. Metabolic syndrome was defined according to the National Cholesterol Education Program-Adult Treatment Panel III, and CKD was diagnosed at an estimated glomerular filtration rate less than 60 mL/(min 1.73 m(2)). The crude and multivariate-adjusted odds ratios (ORs) of CKD associated with MS and its individual components were calculated using logistic regression models in a study population stratified by obesity. The prevalence of MS and CKD was 13.4% and 3.2%, respectively. The association between MS and CKD was significant in obese (OR, 2.91; 95% confidence interval [CI] = 1.34-6.34), but not nonobese (OR, 1.38; 95% CI = 0.60-3.17), subjects. In obese subjects, impaired fasting glucose (OR, 2.47; 95% CI = 1.10-5.57) and high triglyceride levels (OR, 2.42; 95% CI = 1.01-5.83) were risk factors for CKD, whereas no components were significantly associated with CKD in nonobese subjects. Our findings suggest that even in nondiabetic, nonhypertensive Korean adults, early detection and prevention of CKD in obese subjects with MS are critical.