Vitamin D deficiency is common in patients with chronic kidney disease after renal transplantation. Vitamin D, essential for mineral and bone metabolism, also has myriad beneficial autocrine effects on intact immune responses and defense against infection, as well as suppression of malignant changes. Supplementation with oral parental vitamin D could correct this problem. Courbebaisse et al. define how much oral vitamin D to prescribe to renal allograft recipients.