The Fibrous Dysplasia is a benign bone disease, of slow growth and unknown etiology. The involvement of the craniofacial skeleton is not uncommon and, generally, produces facial asymmetries. Case Report: In this article we report the case of a patient with fibrous dysplasia occupying the entire left maxillary sinus with orbitary extension confirmed in the anatomopathological exam. Final Comments: The surgical treatment remains as the main therapeutic approach and the postoperative follow-up is necessary due to this condition recurrent nature.