Malignant mesothelioma of the peritoneum is a rare tumor that must be distinguished from the more common primary peritoneal serous epithelial neoplasms. We report a case of a 66-year-old female presenting with weight loss, anemia, and a large pelvic mass on ultrasound. At laparotomy a large (9x6.5x3.5 cm) mass in the anatomical position of the uterus was found in the minor pelvis. The uterus, tubes and ovaries could not be identified. Palpable paraaortic lymph nodes and liver nodules were found. Immunohistochemically the tumor cells were positive for cytokeratin, epithelial membrane antigen and vimentin-CEA, but S- 100 protein and Leu-Ml were negative. Remnants of the uterine corpus, fallopian tubes and ovaries could not be identified. The overall features were best regarded as malignant peritoneal mesothelioma. There have been reports of mesotheliomas involving the uterus. However, this is the first reported case of mesothelioma causing total replacement of the uterus.