Background:Mesenteric Fibromatosis(MF)is a proliferative fibroblastic lesion of small intestinal mesentery.It constitutes 8%of all desmoid tumours,which represent 0.03%of all neoplasm.It is histologically benign but may invade locally and recur after excision.It occurs sporadically or in association with familial adenomatous polyposis(FAP).Case Report:wepresent a case of a 59-year-old man presenting with three months inguinal hernia non-complicated.On physical exam,his abdomen was distended with abdomial mass.Ultrasonography and CT scan showeda retroperitoeal mass suggestive of GastroIntestinal Stromal Tumor.Colonoscopy and endoscopy showed no polyps.Exploratory laparotomy revealed a mass in ileal mesentery.It was excised along with 30cm of ileum and end to end anastomosis in two layers.Histopathologically was in favor of mesentericfibromatosis.Postoperative days were uneventful and discharged on 7th day.Follow-up for three years which included abdominal utrasonography and colonoscopy did not reveal any new pathological lesions.Considering the rarity of this tumour and difficulties in diagnostic and therapeutic ambit,we believe it is justified to describe this case which came to our observation.