Carcinosarcoma, which consists of both carcinomatous and sarcomatous tissues, is extremely rare in the oral cavity. An 80-year-old woman was referred to us, complaining of a painful, polypoidal, and rapidly growing mass at the lateral border of her tongue. We performed an excision with adequate margin around the stalk of the polyp. The mass was histologically and immunohistochemically diagnosed as a carcinosarcoma composed of both squamous cell carcinoma and rhabdomyosarcoma which is, to our knowledge, the first such case in the tongue. © 2005 Elsevier Ltd. All rights reserved.