Carcinosarcomas are rare tumors of the upper aerodigestive tract, consisting of both carcinomatous and sarcomatous tissue. The larynx and oral cavity are most frequently involved. There has been much controversy regarding the histological nature and clinical course of these tumors. We report a case of carcinosarcoma of the floor of mouth in a 76 year old man who presented with a large pedunculated sublingual mass. There was no evidence of regional or systemic metastatic disease. After local excision, he was followed for one year without evidence of recurrence or metastasis. A review of the literature is presented, with an attempt to clarify clinically relevant aspects of nomenclature, pathogenesis, and clinical course.