An eleven-year-old boy presented with a mass in the right iliac fossa for the last 21 days associated with pain, fever, anorexia, and nausea. The patient was thoroughly investigated and contrast-enhanced CT abdomen revealed a well-defined mass in the region of right iliac fossa. Exploratory laparotomy was done and a mass measuring 10 cm in diameter arising from mesentery of proximal ileum and adherent with the wall of ileum was seen. Resection and anastomosis were done. Histopathological examination showed mesenteric fibromatosis. Postoperatively, patient was well and 3-month followup showed normal recovery.