Inflammatory myofibroblastic tumor (IMT) is a spindle cell proliferation with a characteristic fibroinflammatorv appearance. originallv referred to as an inflammatory pseudotumor, plasma cell granuloma, andxanthomatous pseudotumor. We report a case of IMT of the mandible in a 83-year-old woman. The patient had a tumor in the right side of the mandible, measuring 30×30×20mm. Magnetic resonance imaging showed a lesion with high signal intensity on T2-weighted images and homogeneous enhancement. Histological examination of the surgically removed lesion showed that the tumor was composed of loosely arrayed spindle cells in a background of abundant blood vessels and chronic reactive inflammatory cells, including lymphocytes, plasma cells, neutrophils, and eosinophilic leukocytes. The tumor was reactive for vimentin and actin and negative for desmin, S-100, CD31, CD34, keratin, CAM 5.2, EMA, Ki-67, and ALK 1. Because IMT can be confused with other reactive processes as well as with potentially malignant neoplasms, distinguishing these tumors from histologically similar entities plays an important role in assuring appropriate disease management.