Warthin's tumor is a benign lymphoepithelial neoplasm representing 10 per cent of all parotid gland tumors. Malignant transformation of a Warthin's tumor is an extremely rare event. We report a case of a patient with poorly differentiated carcinoma arising from a Warthin's tumor, as well as review the pathogenesis, histopathology, and surgical management of malignant Warthin's tumors.