Malignant fibrous histiocytoma (MFH) is the most common soft tissue tumor in adult. It is generally regarded as arising from primitive mesenchymal cells that show partial histiocytic and fibroblastic differentiation. Immunohistochemical observations suggest that the expression of smooth muscle markers in the so called MFH is a result of myofibroblastic differentiation. The present study is aimed to correlate between histipathological subtype and clinical parameters, to grade the MFH cases depending on the histopathological criteria for grading, and to examine the cases immunohistochemically for myofibroblastic differentiation using smooth muscle markers in cases of MFH as an aid for accurate diagnosis. This study including 26 soft tissue specimens diagnosed as MFH collected from private and governmental histopathological laboratories in Basrah during the period from January 2000 to October 2005. Additional 4 cases (one leiomyoma, two fibromas and one fibrosarcoma were taken as control positive and negative. Twenty cases of MFH (77%) were in the age group 45-60 years. The mean age was 53.5 year with male to female ratio of 1.3: 1. Nineteen cases (73%) were located in the extremities mainly the lower limbs. Seventeen cases (65.4%) were primary. Twenty two (84.8%) were of pleomorphic subtype, two were myxoid and 2 were inflammatory. All the recurrent cases were regarded as grade III, from the seventeen primary cases fourteen were of grade III, so twenty three cases (88.5%) were of grade III, the remaining 3 cases were of grade II. No grade I tumor was recorded. The majority of pleomorphic subtype cases (95.5%) were of grade III. Both cases of myxoid subtype were of grade II. Desmin expression was found in only 3 cases (11.5%), none for smooth muscle actin or S-100 protein. There was no correlation between desmin expression and tumor site, subtype or grade, as well as, with age and sex of the patients. A strong association between desmin expression and recurrent tumors 33.3% was found.