Children with renal failure generally develop renal osteodystrophy and severe growth failure. Therefore, this study as part of a multicenter, double-blind study (18 institutions) will assess the effects of 1,25-dihydroxyvitamin-D3 on growth, skeletal density, nutritional status, and biochemical parameters of renal failure. There will be an initial 6-month control period, and then patients will be randomized to receive 1,25-dihydroxyvitamin-D3 or dihydrotachysterol.