A patient developed abdominal distension, dyspnea, and nausea due to chylothorax and chylous ascites 1 month after bruising her back. Lymphangiography was unable to identify the site of lymph leakage, and lymphatic duct embolization was impractical. However, lymphangiography showed occlusion of the thoracic duct. Thus, balloon plasty was performed to restore the patency of the thoracic duct, and the chylothorax and chylous ascites improved. Although embolization of the thoracic or lymphatic ducts has been reported as a treatment for lymphorrhea, it is impractical if the lymphatic duct responsible for leakage cannot be identified. In such a case, balloon plasty of the occluded thoracic duct to lower the pressure in the peripheral lymphatic ducts was successfully performed.