Sarcomatoid carcinoma is a rare neoplasm of epithelial origin but consists partly of variable differentiated tumor cells of mesenchymal origin. Accurate diagnosis, including differentiation from adenocarcinoma or gastrointestinal stromal tumor, is difficult. We experienced three cases of sarcomatoid carcinoma of the stomach, and describe the radiological and pathologic findings. One case involved a polypoid mass in the antrum, another a mass with a large ulcer mimicking a Bormann type-II adenocarcinoma in the body, while in the third case, an intraluminal bulky mass arising from the cardia of the stomach was present. This was not differentiated from cancer or stromal tumor.