Objective: Metabolic syndrome (MetS) is a clustering of cardiovascular risk factors and elevated blood pressure is a key risk factor for cardiovascular disease. The relationship between MetS and behavioral aspect of blood pressure(BP) according to the various kinds of measurement method has not been established. Methods: Two hundred ninety eight patients (M:F = 159:139; mean age, 48 짹 12 years) with untreated hypertension underwent office BP (OBP) , Home BP monitoring (HBPM), 24-hour ambulatory BP monitoring (24h ABPM) and central BP(CBP) at multicenter. Also We assessed BP variability from the SD. 112 subjects (M:F =55:57; mean age, 47 짹 11 years) were diagnosed as MetS according to the National Cholesterol Education Program (NCEP) criteria. Results: There were significant differences of OBP, diastolic BP variability on HBPM, systolic morning surge BP, diastolic BP and daytime systolic BP variability on 24h ABPM between subjects with and without MetS (Table). Based on multiple logistic regression analysis, nighttime diastolic BP on 24h ABPM was closely related to MetS (P=0.018; odds ratio = 1.043 [95% CI, 1.007-1.080]). Conclusions: Subjects with MetS have quite different behavioral aspects of BP from subjects without Mets. Especially, the elevation of nighttime diastolic BP is one of the important BP components related to MetS. Key words: self-measured blood presure, 24-hour ambulatory BP monitoring, central BP