BACKGROUND: It used to induce hypercarbia that carbon dioxide insufflated into the peritoneum in laparoscopic surgery. It might stimulate sympathetic nervous system, and decrease splanchnic circulation, hepatic function, and metabolism of anesthetics. The purpose of the present study was to examine the influence of hypercarbia on concentrations of propofol at the time of eye opening and recovery of orientation after propofol target controlled infusion (TCI) during a laparoscopic cholecystectomy. METHODS: Fifty patients were divided randomly into a laparoscopic group (group 1, n = 25) and an exploratory group (group 2, n = 25). A propofol infusion was started at a propofol target concentration of 6microgram/ml, and anesthesia was maintained at 4microgram/ml by using a Diprifusor (TM) turing the operation, intraabdominal pressure was maintained automatically at 12 14 mmHg by a CO2 insufflator and controlled ventilation settings were adjusted about 50 mmHg of PaCO2 after peritoneal insufflation. This ventilatory setting was not changed throughout the operation. We evaluated the estimated plasma concentrations of propofol at the time of eye opening and recovery of orientation in each group using user interface of a Diprifusor (TM). RESULTS: In the laparoscopic group, PaCO2, and PetCO2 increased significantly at 5, 15, 30 minutes after carbon dioxide insufflation, but there was no significant difference in concentrations of propofol at eye opening and orientation after propofol TCI between the two groups. CONCLUSIONS: Hypercarbia induced by insufflation of carbon dioxide into peritoneum didn't give rise to an influence on awakening concentrations after propofol TCI during a laparoscopic cholecystectomy.