A 72-year-old white man presented to Massachusetts Eye and Ear Infirmary with proptosis of the right eye. Computerized tomography (CT) scan revealed a mass which filled the right maxillary sinus and invaded the orbital and middle cranial cavities. Six years earlier, the patient had excision of an ameloblastoma of the right maxillary antrum. The tumor recurred, requiring maxillectomy, local radiotherapy and finally exenteration. Ameloblastoma is a relatively rare epithelial tumor arising from embryonal tooth elements. It is locally invasive and recurrent but rarely metastasizes and extension to the orbit is extremely unusual. The clinical features, histopathologic findings and treatment of this tumor are discussed. Differential diagnosis of jaw tumors, which may invade the orbit, is reviewed.