Lymphangiomatosis is a very rare and slow-growing benign tumor generally accepted to be the result of a congenital malformation of the lymphatic system. It is most commonly found in the neck, axilla and less commonly retroperitoneum, mediastinum, mesentery, omentum, pelvis, bone, skin, scrotum, and spleen. We present a patient who had systemic lymphangiomatosis with splenic involvement. She was presented with the cystic neck mass suspected to be a cystic hygroma during the first decade. She complained of the mass on left upper quadrant of abdomen at the age of 28. Under full investigations, we had diagnosed the lymphangiomatosis involving spleen and right adrenal gland, and splenectomy was done. We present a case of systemic lymphangiomatosis with emphasis on diagnosis, management, and prognosis.(Korean J Med 58:234-239, 2000)