Introduction and Aims: Vascular calcification, a major consequence of secondary hyperparathyroidism (SHPT) due to chronic kidney disease (CKD), likely contributes to the extremely high rates of cardiovascular mortality observed in these patients. Calcimimetic agents effectively decrease parathyroid hormone (PTH) levels and prevent vascular calcification in rodent models of SHPT. In comparison, some studies have shown that low doses of paricalcitol prevented vascular calcification in rodent models of CKD, whereas other reports show that high doses aggravated vascular calcification. AMG 416 is a peptide calcimimetic that substantially lowers PTH levels in CKD patients with SHPT receiving hemodialysis in clinical studies. This study compared the presence and extent of vascular calcification in adenine-induced CKD rats given either AMG 416 or paricalcitol.