Lymphangiomas are malformations of the lymphatic system accounting for approximately 5% of all benign tumors in infants and children. Abdominal lymphangiomas are rare, and can arise from either the retroperitoneum, gastrointestinal tract, or the mesentery of the abdominal viscera. Lymphangioma involving the whole mesentery is particularly rare. Most lymphangiomas are detected during infancy or childhood, but intraabdominal lymphangiomas such as mesentery are not found until adulthood. We report here on a patient with uncommon lymphangioma involving the whole mesentery who presented with fever and abdominal pain. This patient is unusual because he was confirmed through core needle biopsy which showed variable sized lymphatic spaces representing a immunoreactive for D2-40 antibody with involvement of the whole mesentery. No cases of mesenteric lymphangioma confirmed preoperatively have been previously reported in Korea.