A sarcomatoid carcinoma or carcinosarcoma is very rare biphasic tumor characterized by a combination of malignant epithelial and mesenchymal cells. Our case was a-51-year-old female, with palpable mass on rt. lower abdominal lesion. At first, we checked her abdominal CT &diagnosed mucocele /c adenocarcinoma on rt. colon. Then, laparoscopic hemicolectomy &lymph node dissection was performed. But histollogically, the tumor was Sarcomatoid carcinoma, arising in mucinous cystadenocarcinoma in the appendix. The mass size was 9.5cm length approximately &infiltrated the appendix. Immunohistochemically, the tumor cell showed a positive immunoreactions for vimentin &pancytokeratin. It means the tumor has two potential cells; epithelial and mesenchymal cell elements. Scarcomatoid carcinoma of colon is malignant tumor with poor prognosis. The patient was treated with doxorubicin &cisplatin therapy, but we lost the patient. A sarcomatoid carcinoma of colon is extremely rare tumor. We found one case &present it with review of the literatures.