Studies were performed on the aspiration of fluid in the thoracic cavity after pulmonary resection, from the points of tube and mode for suction. Following results were obtained. 1) For aspiration, two tubes (one from the axilla to upper median, another from posterior axilary line in 7th or 8th intercostal space to diaphragm posteriorly) were preferably nsed as compared with one tube. 2) In general, the upper tube is mainly to aspirate air and the lower exudate. The effect of fluid aspiration it invariably related to air leak from the lung and relating reexpansion of the lung. 3) It is better in the result that the length of the tube is about three cantimeters in the upper and nine to twelve in the lower. when a difficulty in expansion is presumed the upper tube is to be six to eight centimeters for getting better aspiration of the fluid. 4) It is better to leave about 200cc of warm saline solution in the thoracic cavity immediately after operation. 5) Horizontal recumbent position is best after opertion.