A new insufflation device for laparoscopic surgery has been developed which permits the persufflation of the abdominal cavity with humidified CO2 at 37 degrees C, with flow rates of 4 l/min/mm of mercury (3 l/min/cm of water) insufflation pressure, i.e. 60 l/min for an insufflation pressure of 15 mm of mercury (20 cm of water). The device consists essentially of an operative laparoscope with a large side opening of 7 mm internal diameter, and a pressure valve limiting the insufflation pressure. The device is safe, since the intraabdominal pressure can never exceed the insufflation pressure. The device has been extensively tested in greater than 500 CO2-laser-endoscopic procedures and has proven to be safe and useful. Smoke can be constantly removed and the pneumoperitoneum is unaffected even by the removal or leakage of large volumes of CO2 from the pneumoperitoneum.