Sevoflurane (CH2F-O-CH(CF3)2) is a fluorinated derivative of ethyl isopropyl ether. Sevoflurane has a blood/gas partition coefficient of 0.60 that allows a rapid induction and emergence of anesthesia. There are several reports that the hemodynamic changes are almost similar to halothane at equipotent dose. But sevoflurane is metabolized to inorganic fluoride known as the etiologic agent of anesthetic nephrotoxicity, more than halothane and isoflurane. Acute renal failure develops in approximately 11% of bumed patients. It is not known whether sevoflurane anesthesia intensifies the renal dysfunction in the early stage, and sevoflurane biotransformation increases in major burn patients, producing higher inorganic plasma fluoride level than non-burn patients, thus increasing the potential for fluoride-induced renal dysfunction. So we studied sevoflurane in the major bum patients. In this investigation we measured the concentrations of serum and urine inorganic fluoride ions before, during and after sevoflurane anesthesia, respectively, with urine volume and osmolality in the major burn patients (n=8). The peak serum fluoride concentration was 30.99 umol/L, 4 hours after anesthesia and then the concentration of serum inorganic fluoride decreased quickly. Peak urinary (fluoride concentration was 1237.73+/-184.27 umol/L, 8 hours after cessation of) sevoflurane, and its concentration was less than 100 umol/L. on the fourth postoperative day. No evidence of abonomal hepatorenal function occurred on the first postoperative day. In conclusion, anesthesia with sevoflurane is safe without significant adverse effects in the major bum patients. Although sevoflurane delivery to major burn patients produced a mean peak serum fluoride level of 30.99 umol/L, no evidence of abnormal renal function occurred in any of the patients in the postoperative period.