Arterial stiffness is a risk factor for cardiovascular disorders and mortality. Arterial stiffness increases progressively with aging. Although nobody can escape from age-related arterial stiffening, having a high-level of cardiorespiratory fitness delays age-related arterial stiffening. The primary components of physical fitness are muscular strength, cardiorespiratory fitness, and flexibility. Recent cross-sectional studies have shown that flexibility is associated with arterial stiffness, independent of muscular strength and cardiorespiratory fitness. In addition, using a 5-year longitudinal study, we found that a greater progression of age-related arterial stiffening was associated with poor flexibility in healthy adults. These cross-sectional and longitudinal studies suggest that flexibility can predict arterial stiffening. In this article, we review the recent studies regarding the relationship between arterial stiffness and flexibility.