A case of chylothorax following an operation for intrathoracic esophageal carcinoma in a 63-year-old man was experienced. Because the patient was obliged to fast for a long postoperative period, thoracic fluid from a drain was yellowish clear and early diagnosis was difficult. In the treatment of postoperative chylothorax, conservative treatment is employed as a rule, and intrathoracic drainage and PEEP for expanding the lung, and TPN and MCT for decreasing the chyle are carried out. For pleurodesis OK-432 and tetracyclines are used, however if the conservative therapy is not effective, operation should be done as soon as possible. Operative procedures include ligation of thoracic duct and convergence ligation right above the diaphragm. In this case suture and closure of defluxion part of the thoracic duct and convergence ligation including around the thoracic duct were effective. A possible occurrence of postoperative chylothorax should be entertained in all thoracic operations.