Two cases of mesenteric cysts are presented. The first case was a five-yer-old boy with bile-vomitting and abdominal pain. At the emergency laparotomy, ileal mesenteric cyst was found with the torsion of the cyst and of the adjacent ileum. The second case was a 2-month-old girl with fever, vomiting and abdominal distension. Ultrasound echogram and CT scan revealed a well-defined, loculated mass. The infected cyst of the descending mesocolon and the narrowing of the descending colon were found at the laparotomy. The resection of the cyst and the adjacent intestine was performed in both cases. In Japanese literatures 171 pediatric cases of the mesenteric cyst were reported until 1987. Ultrasound echogram and CT scan have improved the accuracy of the preoperative diagnosis.
