Inflammatory myofibroblastic tumors are well described in lung and upper respiratory tract of young adults and children. Intra-abdominal forms of the disease are reported to occur most frequently in the liver, followed by stomach, bowel and spleen. A 13-year-old girl who had intermittent fever ranging from 99-101 degrees F of three months period and significant weight loss was referred as a case of pyrexia of unknown origin. The patient was subjected to laparotomy. A solid mass was found arising from the mesentery, four feet from the iliocaecal junction and was adherent to the wall of ileum. The patient became afebrile after the removal of the mass and has gained weight and remained well during the ten months since discharge.