The definition of malignant fibrous histiocytoma (MFH) was modified and simplified in the new WHO-Soft Tissue and Bone Tumor Classification published in 2002. We reviewed the clinical courses of 7 patients with MFH of the retroperitoneum treated in our hospital from 1985 to 2005 and reexamined their pathological diagnoses according to the new classification. All pathological specimens were reviewed again by an expert pathologist (TH) and were confirmed as MFH. Median follow-up was 5 months (0.5 to 44 months). Five patients were diagnosed as having the pleomorphic type, and 2, the inflammatory type. The tumor was located in the retroperitoneal space in 6 patients and around the left spermatic cord in 1. Radical surgery was the primary treatment for 6 patients. The disease recurred locally in 5 patients and distant metastasis developed in 3. The lung and liver were the principal locations of distant metastases. The 2-year disease-specific survival rate was 30% and 2 patients have been alive for more than 3 years. Our experience and those of others reported in the literature suggested that the factors for long-term survival in MFH are pleomorphic-type histology, superficial location, small tumor size and intensive wide excision, although most patients with MFH might have a poor prognosis. Because the tumor size of MFH tended to be large, especially that in the retroperitoneal cavity, wide excision with sufficient tumor-free margin is hard to guarantee.