Epidermoid cyst is a cystic form of teratoma and believed to be derived from trapped embryonic cells along the lines of embryonic closure. A 28-year-old woman presented with a painless swelling over the left mandibular area. On panoramic view, the mandible revealed a 5.5×2.0 cm2 multilocular radiolucent lesion of the left mandibular body and a computed tomography scan showed expansion of both the buccal and lingual plates in the same area. Microscopy found stratified squamous epithelium of the cystic wall and cystic contents of keratinized material. The histological diagnosis wasan epidermoid cyst. The most common location of epidermoid cyst at the head and neck is in the orbit (47%), followed by the mouth floor (23%) and the cervical area (9~24%), but in the jaw bone, it is considered very infrequent. We report the uncommon epidermoid cyst in the mandibular body that had a good healing outcome after treatment with a conservative marsupialization during the 40 months follow-up.