A 6-year-old female was sent to our ER due to nausea, vomiting and abdominal distension for 2 days. This child had a history of constipation and failed intermittent medical treatment for 2 years. Her plain abdominal X-ray showed multiple intestinal loops and under the impression of acute abdomen with mechanical intestinal obstruction, an exploratory laparotomy was performed. A huge mesenteric tumor was discovered to be the cause of the intestinal obstruction; the involved bowel and the mesenteric lymphangioma were resected and primary anastomosis was done. Mesenteric cystic lymphangioma is a rare cause of bowel obstruction; preoperative diagnosis is difficult due to silent clinical course and lack of awareness of the clinical and morphological features of this disease. The case is presented along with a review of literature with the conclusion that a high index of suspicion is recommended. An abdominal ultrasonography may be recommended to evaluate a long-term constipated child to ascertain that any cystic lesion will not be missed.