Chyle is the digestive product absorbed from intestinal lymphatics which the component have high concentration of triglyceride and protein. The various pathological circumstances which give rise to intrathoracic effusion of chyle are well documented and so the etiology is clearly defined in most instances. However, the occurrence of chylothorax in early infancy, in the absence of other demonstrable diseases and without apparent birth trauma, suggests the existence of congenital malformation of the thoracic ducts. We lately experienced a 20 day old new born who was proved to have congenital chylothorax by clinical history and laboratory findings. So we report the clinical findings and laboratory findings with the review of the literatures on congenital chylothorax.