High-molecular-weight adiponectin (HMW ADPN) plays an important role in the regulation of insulin action and atherogenic processes, but the role of HMW ADPN remains to be determined in hemodialysis (HD) patients. In this study, we measured serum total and HMW ADPN in 67 HD patients (age: 67 +/- 14 years, time on HD: 75 +/- 68 months, male/female = 39/28), and examined an association between HMW ADPN and arteriosclerotic parameters such as aortic pulse wave velocity (PWV), cardio-ankle vascular index (CAVI) and ankle-brachial pressure index (ABI). PWV was significantly correlated positively with log-transformed IL-6 (r = 0.33, p < 0.01). CAVI was significantly related to the percentile of aortic calcification area (%ACA) (r = 0.28, p = 0.03) and log-transformed IL-6 (r = 0.25, p = 0.05). ABI was associated negatively with log-transformed IL-6 (r = -0.35, p < 0.01) and %ACA (r = -0.36, p < 0.01), but positively with albumin (r = 0.33, p < 0.01). The HMW-to-total ADPN ratio, a better predictor for insulin resistance, was significantly and positively correlated with PWV (r = 0.34, p < 0.01) and CAVI (r = 0.24, p = 0.05). A multiple stepwise regression analysis revealed that the HMW-to-total ADPN ratio was an independent determinant for PWV and CAVI but not for ABI. The findings suggest that HMW-to-total ADPN ratio may be positively associated with aortic stiffness in HD patients.