Reported is a case of a calcified mesenteric cyst that was causing obstruction of the small bowel. Because only roughly one case occurs per 100,000 hospital admissions, mesenteric cysts are rarely thought of and may be difficult to diagnose. The differential diagnosis includes such critical lesions as aortic aneurysm, pancreatitis, ovarian cysts, omental cysts, and lipomas of the mesentery. The proper treatment of these rare lesions is somewhat influenced by causative factors: embryonic, traumatic, neoplastic, infectious, or degenerative. Surgical excision or enucleation is preferred to internal or external drainage. Ultrasonography is becoming increasingly valuable as a diagnostic tool.