We experienced a case of a 4-year-old girl presenting with vomiting, abdominal pain and mobile mass in the periumbilical area. On physical examination, the abdomen was soft and a 10x10 cm sized, painless firm mobile round mass was palpated in the periumbilical area. An abdominopelvic computed tomography scan showed a huge hypodense mass with encapsulation and multiple septation in the left lower quadrant of the abdomen, compressing the intestinal loops. At operative exploration, she was found to have a soft, yellowish round mass originating from the ileal mesentery, situated 10 cm proximal to the ileocecal valve. The mass was completely excised together with the adjoining ileum, and bowel continuity was restored. Histopathologic diagnosis revealed a mesenteric lipoma, composed of mature adipocytes with no evidence of necrosis or malignancy. The postoperative course was uneventful.