There is accumulating evidence that vitamin D exerts important pathophysiological effects on cardiovascular system. Low vitamin D was associated with increased cardiovascular risk in several reports. We studied the association between vitamin D and arterial stiffness in a random sample of 560 subjects selected from general population. Arterial stiffness was measured as aortic pulse-wave velocity (PWV) using Sphygmocor device. Serum 25-hydroxyvitamin D (25(OH)D) was measured using commercial kits. We found a clear negative trend in aortic PWV among 25(OH)D quartiles. Subjects in the bottom 25(OH)D quartile (<20 ng ml(-1)) showed the highest aortic PWV (9.04 m s(-1)), compared with 2nd-4th quartile (8.07 m s(-1), 7.93 m s(-1) and 7.70 m s(-1), respectively; P for trend <0.0001). The association between 25(OH)D and aortic PWV remained significant after adjustment for age, gender and other potential confounders; subjects in the first 25(OH)D quartile had adjusted odds ratio 2.04 (1.26-3.30) for having aortic PWV ≥9 m s(-1) (top quartile) in multiple regression. In conclusion, we found a clear significant and independent negative association between 25(OH)D and aortic PWV. Subjects with lowest vitamin D status showed the highest arterial stiffness.