Cystic hygroma is a benign neoplasm of lymphatic origin by congenital defect of lymphatic vessel which usually located in the neck, but they may occur in the thorax, axilla, groin or abdomen. Most often it occurs at birth or early in life and composed of large unilocular or multilocular cystic spaces lined with containing serous or serohemorrhagic fluid. On section, they reveal a soft, compressible, spongelike, red-pink tissue that freely exudes a watery fluid to reveal the underlying loose-textured pattern of the mass. Recently the authors had experienced one case of cystic hygroma of the neck. The patient, 10 month old female infant, had a slowly enlarging cystic mass in left, upper cervical area for 8 months. The tumor mass was removed by surgical resection which was confirmed cystic hygroma microscopically.