The present study was designed to determine if etidronate inhibits the development of aortic calcification in hemodialysis (HD) patients. Eighteen Japanese HD patients were divided randomly into etidronate-treated or control groups. Etidronate was given orally at the dose of 200 mg just before sleep on the day of dialysis, which was performed three times per week. In the control group, the aortic calcification area (ACA) increased after 6 months. In the patients who received etidronate, however, when compared to the control group, increases in ACA were significantly suppressed. Serum Ca, P, and the Ca × P product did not change during etidronate treatment. These results suggest that etidronate inhibits the progression of vascular calcification without changes in serum Ca and P levels.