Results from a randomized, placebo-controlled study indicate that ergocalciferol is safe and effective in delaying the onset of secondary hyperparathyroidism in children with stage 2–3 chronic kidney disease (CKD) and vitamin D deficiency. Nine of 20 children on placebo and three of 20 children on ergocalciferol developed hyperparathyroidism after a median follow-up of 12 months. Normal levels of vitamin D were maintained in 88% of children with stage 2 CKD, but only in 45% of children with stage 3 CKD.