A case of large radicular cyst was experienced by authors. The patient was 26 years old male and complaining of slowly growing painless mass of the cheek at the left side for 3 years duration. Under the diagnosis of the radicular cyst, the mass was removed successfully by the Caldwell-Luc's approach and it was proved as radicular cyst in the pathology. The mass was so large as to pass the middle line to the opposite side and protruded anteriorly as large as egg size. So we report this case with some reviews of the literatures.