Amelobl astic carcinoma(AC) is a maJignant coun terpart of ameloblastoma. histologically characteri zed by amelobJastomatolls feature with obviollS cytologic a typi a . AC is a r are malignant tumor with poten t iaJ of metastasis‘ asssllmed to occur far less tha n 1% of ameloblastoma . Nearly 80% of ACs have been reported to occur in the mandibJ e. The allthors reviewed 5 cases of AC in Department of Oral PathoJogy. SeouJ National University from 2005 to 2007 clini copathologically according to age, sex. location and clinical findings. They occllrred at the age from 46 to 75 years wi th average age of 60 Four cases occurred in male and 1 in female‘ showing prediJ ection for ma le‘ While four cases occu rred in the maxilla , including 3 cases in the maxillary molar area and 1 in the maxiJJ a ry premola l‘ a rea, only 1 case occurred in the mandibJe. AC showing predorninance in the maxilla over t he ma ndible in our cases in contrast to other case reviews. Three patients presented painful large oral lllcer at the time of admi ssion, a nd other 2 patients presented swol1en mass around the gingivae and alveoJar bone While the clini cal impression of 3 patients were ma lignant tllmor, other 2 patients were amelboJastoma and nicotine stomatitis. The dllration of symptoms before final diagnosis has ranged from 4 months to 2 years Radiogr a phicalJy they showed poorly demarcated radiolucent lesion with irreg비 ar bony destruction. Resected tumors were measured as 6.0X4.5x4.0cm‘ 0‘ 7xO.5xO.3cm, 5.0 x 4.5 X5.0cm. 0.8xO.6 XO.5cm, and 5cm diametel mass respecti vely. Microscopically lymph node metastasis was confirmed in 1 case, but not in others . The tumors showed basic histologic featu re of ameloblastoma with apparent cytologic atypia sllch as pleomol‘ phism‘ hyper chromatism and atypical ffiJ tOSIS Individua l neoplastic cells displayed wide va riations from case to case‘ showing c lear cells with faint PAS positive granules‘ isolated round cells with abundant cytoplasm. s quamoid ceJls and polygonaJ cell s . [mmunohis toc hemical survey was done in 2 cases. all of which showed positivity to pan-cytoker atin a ntibody and p53 a ntibody‘ but negativity to HMB-45, S-100, and SMA One case recurred twice during 2 yeal's after surgery. But 3 cases showed no evidence of recurrence and metastas is. lt seems to us t hat AC have the potential of metastasis and reCllrrence.