Plasma CO2 gas tension, tidal volume and peak inspiratory airway pressure were investigated before CO2gas insufflation, 30 minutes and 60 minutes after gas insufflation in 32 laparoscopic surgery patients to study the effects of intraabdominal CO2 gas insufflation during laparoscopic surgery under general endotracheal anesthesia with controlled ventilation. Our results were as follows 1) Arterial CO2 gas tension values were significantly higher 30 minutes after CO2 gas insufflation compared to before gas insufflation(36.8±4.2 mmHg vs. 28.3±6.8 mmHg). 2) Tidal volume was increased 30 minutes after CO2 gas insufflation compared to before gas insufflation(505.1±78.2 ml vs. 462.0±83.2 ml). 3) Peak inspiratory airway pressure was significantly increased 30 minutes after CO2 gas insufflation compared to before gas insufflation(16.4±1.7 cmH2O vs. 9.8±1.0 cmH2O). And these increasing states were maintained during laparoscopic surgery. As the above results show, during laparoscopic surgery using CO2 gas insufflation under general anesthesia with controlled ventilation, arterial CO2 gas tension, tidal volume and peak inspiratory airway pressure were significantly increased 30 minutes after CO2 gas insufflation. Cautions may be advised if laparoscopic surgery, by whatever operation, is indicated in subjects who are affected by increasing PaCO2 and peak inspiratory airway pressure.