The case describes an 11-year-old girl affected by an unusually extensive type of polyostotic fibrous dysplasia. The cranium and face and both femurs, tibias, and fibulas were extensively and almost symmetrically involved. Tubulation deformities were noted in the metacarpals and middle phalanges of both hands. These findings appear to represent a very severe manifestation of the disease, as polyostotic fibrous dysplasia is known to be predominantly unilateral. The patient had endocrine dysfunction consistent with McCune-Albright syndrome. Radiological work-up included plain radiography of the skeleton and CT, MR imaging, and MR angiography of the cranium.