Hypovitaminosis D is highly prevalent among patients with chronic kidney disease, especially in those undergoing dialysis. The loss of protein to the dialysis solution seems to contribute significantly to the reduced serum levels of vitamin D in these patients. As a result of the disease and the dialysis procedure, there is high prevalence of chronic inflammation and high risk of infections. There is evidence in other populations, that vitamin D has immunomodulatory effects by stimulating the production of cathelicidin, an antimicrobial peptide and suppressing the production of proinflammatory cytokines. Thus, this study aims to investigate the effects of cholecalciferol supplementation on immunological markers in patients in hemodialysis and peritoneal dialysis with hypovitaminosis D . This is a randomized, double-blind, placebo-controlled trial in which patients who have vitamin D deficiency [25 (OH) D <20 ng / mL] will be allocated to the intervention group (cholecalciferol) or control (placebo). Patients will receive supplemented 100,000 IU / week cholecalciferol a period of 12 weeks. Before and after the intervention will be determined 25(OH)D, cathelicidin, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and C-reactive protein serum. In monocytes, we will evaluate cathelicidin, IL-6 and TNF-α, 25(OH)D receptor and α 1-hydroxylase enzyme expression.