The ameloblastic carcinoma is an extremely rare, aggressive odontogenic neoplasm of the jaws. It is described as an ameloblastoma in which there is histologic evidence of malignancy in the primary or recurrent tumors, regardless of whether it has metastasized. We report an aggressive case of ameloblastic carcinoma of the mandible. A 68-year-old man with the complaint of the left facial swelling and intermittent pain was referred to our hospital. Serial images of panoramic radiograph, computed tomograph, and magnetic resonance imaging showed an ill-defined destructive radiolucent lesion of the left mandible. The lesion had typically aggressive behavior with extensive local destruction of bone and extended to the adjacent soft tissues. Bone scan revealed increased uptakes in the left mandibular body and ramus regions. Histological features were generally resembled with those of an ameloblastoma but with cytologic features of epithelial malignancy.