Ameloblastoma is one of the most common odontogenic epithelial tumors and occurs chiefly between the ages of 20 and 39 years. Reports of ameloblastoma developing before the age of 6 years are rare. We report a rare case of ameloblastoma in the left mandibular region of a 3-year-old Japanese boy, with a review of the Japanese and English literature on ameloblastoma in children younger than 6 years. Intraoral examination showed a marked painless swelling in the left side of the mandible. Radiographic examination revealed a unicystic radiolucency. To treat the tumor, marsupialization was performed twice, with the patient under general anesthesia. There have been no clinical or radiologic signs of recurrence for 4 years 8 months after the second marsupialization.
