Fibrous dysplasia (FD) is a non-neoplastic, expansile lesion of unknown origin. In about one-fourth of cases this disorder affects the head and neck area, where the mandible and maxilla are the most frequently involved sites. Its localization to the ethmoid is a rare event. Since the disease slowly progresses, its management is delayed until significant clinical symptoms or non-well-tolerated aesthetic deformities are present. When required, surgery is the treatment of choice. Several external procedures have been used to manage the lesion, but recently, more conservative transnasal approaches have been proposed. We report the history of a 6-year-old boy with fibrous dysplasia of the ethmoid labyrinth that underwent successful transnasal endoscopic removal. Furthermore, an analysis of the literature is presented with particular emphasis on clinical picture, diagnosis, and treatment of this rare illness.