Cystic lymphangioma is an uncommon mesenteric tumor which is usually reported in children. We describe a case of a 12-years old girl who was admitted in our hospital with abdominal distension and pain. Physical examination showed an abdomino-pelvic mass. Preoperative studies including abdominal ultrasonography and computed tomography failed to determine the cause of the pain. Laparotomy found a giant cystic tumor of the small bowel mesentery. Histological studies confirm the diagnosis of cystic lymphangioma. Based on this case, a review of the literature is suggested.