We report a case of glandular odontogenic cyst (GOC) arising in the mandible. The patient was a 55-year-old woman who presented with a painful swelling of the right premolar region of the mandible.Roentgenographic examination revealed a multilocular radiolucent lesion from the right first molar across themidline to the left second premolar region. The clinical diagnosis was a mandibular cyst. Enucleation of the cystand extraction of the teeth were performed with the patient under general anesthesia. Histological examinationshowed a multicystic lesion partially lined by non-keratinized epithelium with focal plaque-like thickening. Thesurface epithelium included eosinophilic cuboidal and ciliated cells. Cyst-like spaces and glandular structureswere also observed within the epithelium. Epithelial islands were also seen in connective tissue of the cyst.Immunohistochemically, epithelial cells were strongly positive for cytokeratin (CK) 13 and 19, but almost negativefor CK18. The histological diagnosis was GOC. The postoperative course was satisfactory, and no recurrencehas been noted 4 years 6 months after the operation.