Introduction: We evaluated the associated factors of serum magnesium in patients on maintenance hemodialysis (MHD). Furthermore, we evaluated the relationship between low serum magnesium and arteriosclerosis in these patients. Methods: In 129 patients on MHD, we evaluated the blood levels of magnesium, brachial-ankle pulse wave velocity (ba-PWV), ankle-brachial index (ABI), and intima-media thickness of the common carotid artery (IMT). Findings: In MHD patients, the serum level of magnesium was significantly correlated with age, calcium, TNF-, albumin, and ba-PWV but not with ABI or IMT. In the multiple regression analysis, albumin (P=0.0001, =0.31) and calcium (P=0.029, =0.18) were selected as significant predictors of the magnesium level in MHD patients. Furthermore, the serum level of magnesium, as well as systolic blood pressure (P=0.0001, =0.32) and age (P=0.005, =0.25), were selected as significant (P=0.012, =-0.22) predictors of ba-PWV in MHD patients. Discussion: In MHD patients, the serum magnesium level was associated with the serum levels of calcium and albumin. Furthermore, a low serum magnesium level in MHD patients was associated with the index of vascular stiffness.