The peripheral ameloblastoma is a rare tumor of the oral cavity, of which relatively few well-documented cases have been reported. A 54-year-old Caucasian male was found to have such a lesion in the posterior maxilla. The origin, histological appearance, and surgical treatment of this lesion is discussed. Histologically, the peripheral ameloblastoma is indistinguishable from the basal cell carcinoma, the occurrence of which is controversial in the oral cavity.