We analyzed the clinicopathological features of 9 breast malignant fibrous histiocytoma (MFH) patients. Immunohistochemistry was used to make both diagnosis and differential diagnosis, and to identify prognostic factors. All tumors lacked epithelial markers but expressed mesenchymal markers, suggesting a mesenchymal origin. Of the five cases expressing Ki-67, two of three patients with axillary lymph node involvement died between 6-8 months, and two died at 17 and 26 months after diagnosis. The two remaining cases, with low Ki-67 expression, had no recurrent or metastatic disease at 145 months after diagnosis. Previous studies have shown that surgery is the primary treatment of choice, but no clear benefit from adjuvant chemotherapy was observed. We demonstrate that axillary lymph node involvement and high expression of Ki-67 are associated with poorer prognosis. A literature review indicates surgery remains the first choice for MFH, but benefits from adjuvant chemotherapy remain unclear.