Omental and mesenteric cysts are rare intra-abdominal lesions which may be congenital, traumatic, neoplastic or infectious in origin. They give rise to non-specific clinical features and may be a cause of the surgical acute abdomen, especially in children. Correct preoperative diagnosis is infrequent but a high index of suspicion and use of ultrasonography when available would improve clinical diagnosis. Six omental and mesenteric cysts encountered in five children over a 10-year period (1978-87) are reported. All the cysts were congenital. Three patients presented with non-specific symptoms and two presented with acute abdomen. Correct preoperative diagnosis was made in two patients. All five patients had surgery. Two had enucleation of the cysts, two had excision of the cysts with adjacent bowel segment and one patient with two cysts had partial excision of the wall of the cysts with free internal drainage into the peritoneal cavity. All patients survived.