Since the first report of the ectopic tooth by Albinus in 1754, there have been many reported cases with odontogenic cyst. Recently, the authors experienced two cases with large odontogenic keratocyst which is one of the variations originated from dentigerous cyst in the maxillary sinus due to unerupted tooth. These were removed successfully by was of Caldwell-Luc's approach, and that were proved as odontogenic keratocyst. So we report this cases with some reviews of the literature.