Mesenteric cystic tumors or mesenteric cysts are defined as cystic masses located in the mesentery.  They are rare malformations with estimated incidence to be 1 in 100.000 in the adult population and 1 in 20.000 in the pediatric population with a 1:1 male to female ratio. Usually they are benign growths with malignant transformation reported in 3% of cases and they usually present in the first decade of life. Mesenteric cysts are often incidental findings on physical examination or imaging in about 40% of cases, but they can cause unspecific abdomainal symptoms. In this article is presented a case of a 14–year–old girl with a giant cystic mucinous mesenteric tumor.