Post-operative pulmonary complications have been discussed as to causes and preventive methods for a long time. One of these methods is intermittent positive pressure breathing(IPPB) which has been widely advocated, but there are many debates now. We studied the relationship of post-operative pulmonary complications with patient's age, general condition and operation site & duration of IPPB. The results were as follows: 1. The rate of IPPB was 8. 4% of general anesthetic patients. 2. The ratio of medical to surgical patients on in IPPB was 1: 10. 3. We had 13 post-op. pulm. complications with prophylactic IPPB and 4 cases without IPPB. 4. The incidence of post-operative, pulmonary complications increased with the patients age, operative time, number of class in physical status (by ASA) and increased particularly after upper abdominal surgery more than lower abdomen or other sites.