In this study, the changes of composition and volume of air which insufflated in rabbit uterine cavity were observed. Expeimental rabbits were laparatomized and air introduced through cervical by means of air introducer and ligations were done in uterotubal end and cervical portion prior to air insufflation. The air was withdrown through needle puncture into the uterine wall at 1,3,6,12 and 24 hours following air insufflation. The volume was measured and concentration of gas was analyzed by Scholander microgas analyzer. The results obtained were summerized a follows: 1. The changing composition rates of insufflated air (O2 and CO2) were more rapid in high pressure group than in lower pressure group. 2. The composition changes of air (decreased O2 concentration and increased CO2 concentration) were more rapid in large volume group than in small volume group. 3. The composition changes of O2 concentration showed significant decrease in an hour, then gradually decreased up to 24 hour. And CO2 concentration increased sifnificantly in an hour, then gradually increased up to 24 hour. 4. The insufflated air volume showed decreasing 63.3% in an hour, 59.6% in 3 hour, 57.0% in 6 hour, 49.3% in 12 hour and 40.8% in 24 hour.