Increased arterial stiffness is associated with risk variables of metabolic syndrome in middle-aged and older adults. However, information regarding the influence of the metabolic syndrome on arterial stiffness and its rate of change with age in young adults is limited. These aspects were examined in a sample of 806 asymptomatic, healthy young adults aged 24-44 years from a black-white community. Brachial to ankle pulse wave velocity (baPWV) measured by an oscillometric method was used as an index of arterial stiffness. baPWV increased with the increasing number of metabolic syndrome components, defined by National Cholesterol Education Program Adult Treatment Panel III (1256, 1314, and 1422 cm/s for those with 0, 1-2, and 3-5 components, respectively, P for trend <0.001). Furthermore, the rate of change (slope) of baPWV with age increased as the number of metabolic syndrome components increased (4.1, 10.7, and 18.7 cm/s per year for those with 0, 1-2, and 3-5 components, respectively; P for comparison of slopes <0.001). These findings by showing the deleterious effects of metabolic syndrome on arterial stiffness and its age-related increase in young adults underscore the importance of this syndrome in cardiovascular risk assessment even in a younger population. Further longitudinal studies are needed to confirm the current cross-sectional findings.