Fibrous dysplasia affects principally the bone, it might also comprise extra skeletal anomalies; whereby the bone is replaced by a dysplastic fibrous tissue. It is classified according to the number of affected bones, and its association to endocrine alterations in: monostotic, polyostotic forms and Albright's disease. A congenital etiology is suggested. Pathologic fractures are the most frequently associated complications. We present a case with a polyostotic form of fibrous dysplasia in a 13 years old Colombian girl, wherein a differential diagnosis and treatment decision was made.