The ameloblastoma is an odontogenic epithelial tumor and is histologically similar to the embryonic tissue that produces enamel during tooth formation. These tumors are histologically benign but are locally aggressive with a marked tendency for recurrence. In rare circumstances the ameloblastoma has been known to act in malignant fashion. The author has recently experienced an ameloblastoma of the mandible in 51-year-old female patient whose chief complaint was painless swelling of the jaw. The tumor was successfully removed by means of complete excision and partial mandibulectomy under the general anesthesia.