Inflammatory myofibroblastic tumor or inflammatory pseudotumor is characterized by spindle cell proliferation with inflammatory cell infiltration, predominantly plasma cells and lymphocytes. We have experienced a case of inflammatory myofibroblastic tumor of the mesentery in a 57-year-old male patient with intermittent abdominal pain. On computer tomography, a well demarcated mass was seen in the mesenteric side of the ascending colon. Right hemicolectomy was performed under the impression of the metastatic tumor of lymph nodes. Grossly, a rather well-circumscribed gray white mass was noted in the mesentery of the ascending colon. Microscopically, the lesion consisted of plump spindle cells and accompanying inflammatory cellular infiltrates. The spindle cells were positive for vimentin.