Background: The metabolic syndrome (MS) is associated with increased vascular disease risk. Little is known whether functional or structural changes are differentially affected by the MS in subjects with or without hypertension. The aim of this study was to analyze the impact of the MS on carotid ultrasound traits and arterial stiffness in hypertensive and normotensive subjects. Methods: A total of 616 subjects (hypertension, 270; normotension, 346) were enrolled. None of subjects had diabetes, pharmacologic treatment of hypertension or dyslipidemia. All subjects underwent heart-femoral (hf) and brachial-ankle (ba) pulse wave velocity (PWV) determination by an automatic wave form analyzer and carotid ultrasound examination for measurement of intima-media thickness (C-IMT) and detection of plaque. Results: Hypertensive patients with and without MS did not significantly differ by age (51짹11 vs 52짹10 yr), sex distribution (male, 67.9 vs 66.2%), SBP (156짹17 vs 153짹17 mmHg), DBP (96짹10 vs 95짹9 mmHg), hfPWV (1011짹167 vs 979짹139 cm/s), baPWV (1601짹285 vs 1564짹228 cm/s), C-IMT (0.73짹0.11 vs 0.72짹0.11 mm), presence of plaque (30.6 vs 25.0%) (all, p=NS). Normotensive subjects with and without MS did not significantly differ by age (51짹10 vs 49짹10 yr), but significantly differ by sex distribution (male, 58.9 vs 71.4%), SBP (127짹7 vs 119짹10 mmHg), DBP (80짹6 vs 75짹8 mmHg)(all, p<0.05). hfPWV was similar (852짹111 vs 823짹126 cm/s, p=NS), but baPWV was not (1359짹151 vs 1308짹197 cm/s, p=0.02). C-IMT and presence of plaque were significantly higher in subjects with MS compared with those without MS (C-IMT, 0.70짹0.12 vs 0.65짹0.09 mm; plaque, 29.4 vs 16.5%, both p<0.05). After control of age, sex, SBP, total cholesterol and smoking, the difference in baPWV lost its statistical significance, but C-IMT did not. Conclusion: This suggests that the MS status affects more atherosclerotic process than stiffnening of aorta in normotensive subjects.