Background: A mesenteric cyst is defined as any cyst located in the mesentery; it may or may not extend into the retroperitoneum, which has a recognizable lining of endothelium or mesothelial cell. Mesenteric cyst can occur anywhere in the mesentery of gastrointestinal tract from duodenum to rectum. The pathology of this case is unknown and it is asymptomatic. The case is confirmed by lab report and histology report. Case Description: A 34 year old woman presented with abdominal pain since 4days. On the physical examination found the history of surgery and there is no any medical history. On the physical examination the palpable mass is presented at the right upper side of the abdomen. In USG report a giant mesenteric cyst was found at 60 cm distal to the ligament of Treitz, which was enveloped by 60 cm of the jejunum. Conclusion: Mesenteric cyst is rare benign abdominal tumor, it is difficult to diagnose because of non-specific clinical symptoms is present in this disease condition. Exploration surgical procedure is the gold standard approach for the, management of giant chylous mesenteric cyst.