A case of endometrial ciliated carcinoma mixed with foci of mucinous adenocarcinoma and argyrophil cells is described. The patient suffered from diabetes mellitus, hypertension and obesity, but had no history of estrogen use. Although the tumor presented well differentiated histologic features, it showed complete diffuse, endophytic extension. Approximately half of the cilia had abnormal inner structures, with 8 + 2 microtubular pattern. Some ciliated cells contained intracytoplasmic mucin, while others contained neurosecretory granules. These findings suggest that malignant ciliated cells have the capacity of further transformation into mucinous or endocrine cells.