The authors have recently experienced a case of a large ameloblastoma causing a marked disfiguration of the face with complaints of nasal obstruction, headache and rhinorrhea. The tumor mass was located in the right maxillary sinus. It was successfully removed by means of Caldwell-Luc's approach. There were two unerupted teeth in the tumor mass, morphologically resembled permanent lateral incisor and canine, and the former was embeded in the mass near the posterior wall of the maxillary antrum, the latter was located in the tumor mass and gum. The deciduous lateral incisor was also impacted in the gum, but the deciduous canine was located at normal position. These all were extracted. The postoperative course was also uneventful.