We have experienced an unusual case of mesenteric lymphangiomatosis in a 6-month-old male infant. Computedtomography (CT) disclosed fatty abdominal masses with attenuation coefficient being -5 ~ -28 Hounsfield units(HU). Laparotomy disclosed innumerable small and large chyle containing masses in the mesentery as well asmesenteric root. Pathologically these were confirmed to be cavernous and cystic lymphangiomatosis. One must bearin mind the possibility of lymphangioma in case of fat containing mesenteric mass on CT.