Introduction: Fibrous Dysplasia is a rare benign bone disorder with unknown aetiology; consists in replacement of normal medullary bone by fibroosseous tissue, causing distortion and overgrowth of the bones involved. Entity with nonspecific clinical presentation (whose symptoms may include olfactory disorders - due to involvement of the cribriform plate or surrounding areas); whose suspected diagnosis is established by test-imaging and definitive diagnosis requires histological confirmation. Treatment depends on symptoms' severity, location and impact on patient quality of life and it goes from conservative treatment (in asymptomatic or mild cases) till surgical excision (in severe ones). It has a 0.4% malignancy incidence rate and a capacity for local recurrence of up to 25%. Therefore, requires a long-term follow-up. Case Report: A 78-year-old woman was referred for evaluation of an olfaction disorder that began six months earlier, with no other neurological or ENT associated symptoms. After a detailed anamnesis and a complete physical examination, which turned out to be normal, test-imaging was requested reporting an altered signal in the right sphenoethmoidal junction, with no apparent intracranial extension, associated with a pattern consistent with Fibrous Dysplasia. Due to mild patient symptomatology's (only parosmias), medical treatment (oxcarbazepine) was proposed -with improvement thereof-, and later controls. Keywords: Fibrous Dysplasia, Olfaction Disorders, Paraosmia. 2