Mesenteric and omental cysts are rare intra-abdominal lesions in childhood, and may present various clinical features such as an asymptomatic mass or an acute abdomen. Therefore, these entities are frequently misdiagnosed preoperatively or are found only incidentally at operation for other conditions. We analyzed our experiences of 19 cases in a 19 year period from 1981 to 1999, at College of Medicine, Catholic University of Korea. There were 12 boys and 7 girls with a mean age of 4.8 years (range, 3 days to 15 years). Common presenting symptoms were abdominal pain (47%), abdominal distension (31%), abdominal mass (24%), vomiting (15%) and fever (10%). Ultrasonography was the most preferred method of diagnosis. Other diagnostic modalities include CT, MRI, and abdominal ascites tapping in selected patients. Location of the mesenteric cysts was small bowel mesentery in nine, the right mesocolon and retroperitoneum in one, the left mesocolon in one, and the jejunum, sigmoid-colon mesentery in one. Most of the patients underwent cyst excision, but six patients required concomitant bowel resection for complete removal of the lesions, and two patients underwent unroofing and simple aspiration respectively. There was one mortality case due to sepsis.