['Vitamin D insufficiency is related to erythropoietin resistance in chronic kidney disease (CKD). This study was conducted to evaluate the effect of ergocalciferol on the dose of erythrocyte-stimulating agent (ESA) administered to children with CKD stage 5 and vitamin D insufficiency.', 'Twenty patients aged <18 years with CKD stages 5 or 5D and vitamin D insufficiency were divided into two groups. During the 12-week study, ten patients received oral ergocalciferol (treatment) whereas the other ten patients did not (control). The ESA dosage was recorded monthly.', 'There were no significant differences in demographic data, ESA dosages, and laboratory data, including corrected calcium, phosphorus, parathyroid hormone, hemoglobin, ferritin, 25-hydroxyvitamin D (25D), and transferrin saturation levels, between the two groups at baseline. At the completion of the study, serum 25D levels in the treatment group were significantly increased from baseline (p = 0.02) and were significantly higher than the serum 25D levels in the controls (p < 0.005). The ESA dosage in the treatment group was significantly decreased when compared to baseline (p = 0.04).'] Does ergocalciferol decrease erythropoietin resistance in children with chronic kidney disease stage 5?