The ameloblastic fibro-odontoma (AFO) is a rare, mixed odontogenic tumor exhibiting the histological characters of the ameloblastic fibroma and complex odontoma. It is comprised of proliferating ectodermal and mesenchymal components of odontogenic tissue as well as enamel and dentin. AFO normally presents as an asymptomatic swelling of the posterior maxilla or mandible and is usually associated with developing teeth, occurring predominantly in children and adolescents. Such lesions are generally found upon radiographic examination of patients whose tooth eruption is delayed. This lesion often includes an unerupted permanent tooth, and extraction of this tooth is a common treatment. The purpose of this report is to describe an AFO in the posterior mandible of a nine-year-old girl for whom enucleation was performed under general anesthesia without extracting the displaced permanent mandibular left second molar. Two years later, the tooth erupted into occlusion without tumor recurrence.