Recently, many investigators have reported that treatment with vitamin D improves outcomes of patients with chronic kidney disease. Though the detailed mechanisms have remained unclear, it has been speculated that such a treatment may prevent progression of chronic kidney disease and cardiovascular disease. It has been reported that Vitamin D may attenuate renal injury and ameliorate renal function and proteinuria. In addition, several studies have shown that vitamin D may prevent progression of atherosclerosis, vascular calcification and left ventricular hypertrophy. The emerging experimental and clinical evidence has suggested that vitamin D may protect kidney and cardiovascular system.