Two patients who developed malignant fibrous histiocytoma in previous surgical sites are reported. One patient developed malignant fibrous histiocytoma in an amputation site, and the other patient developed it in a previous hernioplasty scar. Both patients presented with a mass, clinically interpreted as a subcutaneous abscess. The light microscopic and fine structural features of these tumors are described. A possible causal relationship between previous surgery and malignant fibrous histiocytoma is discussed in view of other reported cases arising in various conditions following chronic reparative reactions. Cancer 53:176β183, 1984