We report a case of mesenteric lymphangioma in a 55-year-old man suffered from progressive abdominal pain. While neutrophilia was observed from the hemogram, his physical examination showed diffuse abdominal tenderness. A massive and lobulated mass measuring 23 cm x 21 cm in size at lower abdomen, and pelvic cavity involving dilated bowel and mesentery were shown in computerized tomogram. The man received an operation where a segment of small intestine measuring 67 cm in length was excised. The mesentery showed marked swelling and soft and fluctuant palpation. Sponge like multicystic structure was also found on cut surface. Microscopic examination showed a mesenteric cavernous lymphangioma characterized by multi thin-walled and dilated lymphatic vessels lined by a flattened endothelium and frequently surrounded by lymphocyte aggregation. Immunohistochemical examination found D2-40 The lining endothelial cell was found to be positive for D2-40 from. The man experienced no tumor recurrence in the following years.