Ameloblastoma is a tumor of odontogenic epithelium that occurs in the jaws. We describe a case of an ameloblastoma of the maxilla that was diagnosed by fine needle aspiration cytology. The patient presented with a mass in the left maxillary sinus. Cytologic examination of the aspirate material showed numerous sheets of tightly packed basaloid cells. Several sheets of cells were surrounded by a row of columnar cells, with the nuclei oriented away from the basement membrane (peripheral palisading). Histologic examination of the resection specimen confirmed the presence of an ameloblastoma of the maxilla.