Aim To investigate whether high blood glucose-induced vascular calcification in diabetes mellitus is caused by the endoplasmic reticulum(ER) response and subsequent apoptosis. Methods We examined the effects of high glucose on the ER stress response and calcification of vascular smoothmuscle cells (VSMC). Alkaline phosphatase (ALP) activity, calcium content and osteogenic markers expression was measured by colorimetric assay, o-cresolphthalein method and Western blot analysis. Results High glucose induced osteoblastic differentiation and ER stress of VSMC,as evidenced by ALP activity, calcium content and osteogenic markers expression increase. 4-PBA treatment could inhibit ER stress and apoptosis of VSMC, therefore, high glucose-elicited VSMC calcification was retarded. Conclusion High glucose can activate ER stress and osteoblastic differentiation in VSMC, ER stress and apoptosis might mediate VSMC calcification induced by high glucose.