Malignant neoplasms consisting of both epithelial elements and mesenchymal components are extremely rare in the sinonasal tract. These tumors, variously termed malignent teratoma, blastoma, teratocarcinoma or teratocarcinosarcoma, probably comprise a homogeneous group of neoplasms since their histological and biologic features are essentially similar. Histologically, these tumors are characterized by mixture of epithelial elements and mesenchymal components with immature or embryonal characteristics. These tumors are locally aggressive and may invade soft tissue, bone, orbit and cranial cavity. The authors have experienced a case of teratocarcinosarcoma treated with surgical resection and radiation.