BACKGROUND: A decrease in core body temperature caused by heat distribution depends on the anesthetic agent used. The purpose of this study is to investigate the effects of sevoflurane and propofol on core temperature during laparoscopic major abdominal surgery requiring pneumoperitoneum of more than 90 min. METHODS: Fifty adult patients undergoing laparoscopic major abdominal surgery were randomly assigned to either a sevoflurane group (n = 25) or a propofol group (n = 25). In the sevoflurane group, anesthesia was induced with propofol 2 mg/kg, remifentanil 1.0 microg/kg, and maintained with 0.8-2.0 vol% sevoflurane and 0.1-0.2 microg/kg/min remifentanil. In the propofol group, anesthesia was induced with the effect-site concentration of propofol of 5.0 microg/ml and remifentanil 4 ng/ml, and maintained with the effect-site concentration of propofol of 2-3.5 microg/ml and remifentanil 3-5 ng/ml. Core body temperature was measured with an esophageal stethoscope with a temperature sensor after the start of the pneumoperitoneum (baseline) and at 15-min intervals until completion of surgery. RESULTS: During the study period, core temperature was comparable between the two groups. When compared with baseline values, core temperatures in both groups were significantly decreased 45 min after pneumoperitoneum. CONCLUSIONS: This study demonstrated that in patients undergoing prolonged laparoscopic surgery, a decrease in core body temperature during sevoflurane-remifentanil anesthesia was not different than propofol-remifentanil anesthesia, and the incidence of hypothermia of the two groups did not differ.