This study will enroll chronic kidney disease patients, stage 3 and 4, who have low serum vitamin D levels as defined by K DOQI Guidelines. Patients will be randomized to receive oral daily ergocalciferol or paricalcitol. A total of 80 patients will be enrolled, 40 in the cholecalciferol group and 40 in the paricalcitol group. Outcomes will be assessed as proportion of patients achieving pre-defined changes from baseline and as absolute changes from baseline values. Baseline values will be determined from averaging two consecutive measurements of the variables of interest prior to randomization.