Metabolic syndrome (MS) has 2 conflicting factors: obesity known to be protective against osteoporosis and an inflammation that activates bone resorption. The aim of this study was to evaluate the difference of bone mineral density (BMD) in women with or without MS according to menopausal state. This is a cross-sectional study of 2,265 women (1,234-premenopausal, 931-postmenopausal) aged over 20 years who visited the Health Promotion Center from January 2006 to December 2009. We measured BMD at the lumbar spine and femoral neck. MS was defined according to the American Heart Association/National Heart, Lung, and Blood Institute (AHA/NHLBI) criteria. The prevalence of MS was 5.5% in the premenopausal group and 13.5% in the postmenopausal group. In the postmenopausal group, C-reactive protein (CRP) was significantly higher in subjects with MS than those without MS, but it was not in the premenopausal group. In the postmenopausal group, women with MS had a lower BMD at the lumbar spine and femoral neck before or after adjustment. In the premenopausal group, women with MS had a lower BMD at the lumbar spine, but not at the femoral neck. In stepwise linear regression analysis, predictive variables for BMD of the lumbar spine were systolic blood pressure in the premenopausal group and HDL-cholesterol and diastolic blood pressure (DBP) in the postmenopausal group. The predictive variables for BMD of the femoral neck were DBP and waist circumference in the premenopausal group and CRP and DBP in the postmenopausal group. Inflammation might have a more important role in BMD than obesity in the postmenopausal women.