We have experienced a case of left side chylothorax following the operation of PDA and lung cancer. A 26-years old woman visited to Inje medical college Pusan Paik hospital with frequent upper respiratory infection and dyspnea on Exertion. The result of the series of studies, she has been PDA and lung cancer, and then simple ligation of PDA and left pneumonectomy was performed. At 6days after operation, chylothorax was detected. The chylothorax was treated with conservative treatment only thoracentesis, NP0 and IV hyperalimentation