In relation to a case of multiple fatigue fractures definitely diagnosed by scintigraphy and xerography, the authors report two other previous cases of spontaneous fractures at a single site in which the diagnosis was made only after surgical biopsy and histological examination. Recalling the frequent confusion arising in children between periosteal appositions and osteomyelitis or Ewing's sarcoma, and the different radiological phases of this type of fracture, they stress the necessity for a maximum effort to demonstrate the key element in the diagnosis: the cortical fissure. The latter is often minimal, at the limit of visibility and developing late. Thus repeated examinations and the use of special radiological techniques are necessary.