1 The status of the air leak and blood effusion after the segmental pneumectomy was studied using the three bottle catheter suction drainage as the aspiration apparatus. Silicone rubber drain pipe (0.8cm in inside diameter, 1.5cm in outside diameter and 90 cmin length) was used and no closure by clotted blood was experienced by the time the drain pipe was drawn out, that is 72 hours after operation. It was in good condition to observe the air leak. 2. The air leak stops the quickest in 10 hours but mostly in 12 hours to 48 hours. Yet there are some that continues more than 60 hours. 3. The intermittent insufflation after the segmental pneumectomy was performed with the I. P. P. B. apparatus (Bentt), and the air leak, re-expansion, complication etc. were examined compared with that of the non-insufflation. 4. By this positive re-expansion of the lung after the segmental pneumectomy the air leak stops mostly in 6 hours to 24 hours. Furthermore it shows good re-expansion of the lung and no combined symptoms by insufflation can be found.