Dentigerous cysts have been reported since 1754, reported by Albinus. Recently, the author has experienced a case of a large dentigerous cyst, encroached through entire right maxillary sinus and partially left maxillary sinus, even originated from left side. Dentigerous cyst has had more significant meaning, because some authors had reported malignant change of this cyst. This cyst was removed successfully by means of Caldwell-Luc's operation without any marked disfigurations or complications.