A 16 month old male infant was found with slip down state in a bath room without evidence of trauma to whole body. The infant was treated with several thoracentesis and closed drainage due to persistent right pleural effusion at other hospital and transferred to our hospital for further evaluation and treatment at July 2003. The pleural effusion was confirmed as chylothorax by chemical analysis. He was treated with parenteral feeding for 21 days. Because the amount of chest tube drainage was about 110∼210 cc/day, and could not be decreased with conservative treatment. patients underwent ligation of thoracic duct. Post-operative course was uneventful except post-op. empyema thoracis, The open drainage tube was removed at post operative 30 days, The patient was in very good condition with complete cure until post-operative 3 months.