Background. Pure rhabdomyosarcoma of the uterus is an exceedingly rare tumor, While there are no commonly associated tumor markers, a previously reported case confirmed CA125 production by a pure uterine rhabdomyosarcoma. Case. We describe a postmenopausal woman who presented with vaginal bleeding and was diagnosed with pleomorphic rhabdomyosarcoma of the uterus. Of particular interest was an elevated serum CA125 level at presentation. Immunohistochemical staining with CA125 antibody, however, showed no activity within the tumor. Despite aggressive therapy, the patient experienced distant nodal metastases and succumbed to the disease within 25 months of diagnosis. Conclusion. Our patient illustrates the typical presentation and aggressive behavior of this rare neoplasm. While serum CA125 may be a useful tumor marker in selected patients, elevated levels do not directly reflect tumor burden when associated with negative immunohistochemical staining.