Metabolic syndrome is a powerful predictor of cardiovascular disease in hypertension, and large-artery stiffness is increasingly recognized as a cardiovascular risk factor. We hypothesized that the adverse prognostic significance of the metabolic syndrome in hypertension might be explained in part by its association with aortic stiffness. A total of 169 newly diagnosed, never treated, nondiabetic patients with essential hypertension (men 55%, 48±11 years) were classified by the presence (n=45) or absence (n=124) of the metabolic syndrome. All patients underwent aortic and upper limb pulse wave velocity determination by means of an applanation tonometry-based method. Aortic pulse wave velocity had a direct correlation with office and 24-hour systolic pressure ( r =0.42 and 0.31, respectively), as well as with waist circumference ( r =0.35, all P <0.001), but not with body mass index ( r =0.10, P =not significant). Aortic pulse wave velocity was higher in the subgroup with the metabolic syndrome (10.0±2.7 versus 8.8±2.1 m/s; P =0.003), whereas upper limb velocity did not differ in the 2 groups (8.6±1.4 versus 8.7±1.5 m/s; P =not significant). In a multiple regression, aortic pulse wave velocity was independently associated with age, systolic blood pressure, and the metabolic syndrome. Only diastolic BP independently predicted upper limb pulse wave velocity. We conclude that in untreated hypertension, the metabolic syndrome is independently associated with a higher aortic, but not upper limb, pulse wave velocity. Central, but not general, adiposity is an important determinant of aortic stiffness in hypertension.