Ten children with histiocytosis X with vertebral column involvement were followed through the natural course of the disease. The characteristic roentgen findings were (1) a variable degree of collapse of a vertebral body, (2) no thinning or thickening of the adjacent intervetebral discs, and (3) absence of a soft-tissue mass. The natural history was one of restoration of varying degree in vertebral height. This could occur even though there had been almost complete collapse (vertebra plana) at the onset of the disease. Neurological complications were rare and the eventual outcome of all the patients did not appear to be affected by the type of treatment given.