Objective：To observe the effects of sevoflurane inhalation in advance on pulmonary function and oxidative stress responses during one-lung ventilation（OLV）. Methods：Sixty patients preparing to undergo radical esophageal cancer resection were randomly divided into 3 groups equally（n=20）：sevoflurane inhalation in advance group（group SP）；propofol group（group P）；sevoflurane group（group S）. Anesthesia was induced with midazolan 0.04 mg/kg，fentanyl 3-4 μg/kg and propofol was administered by target con－trolled infusion with target blood concertration of 3 μg/ml. Tracheal intubation was facilitated with rocuronium of 0.6-0.8 mg/kg. Anesthesia was maintained with propofol at a target blood concertration of 3 μg/ml in group P or inhalation of sevoflurane（1.0%-3.0%） in group S. Anesthesia was maintained with the inhalation of sevoflurane（1.0%-2.0%） before OLV and with propofol after OLV in group SP. Remifentanil was infused by target controlled and atracurium was given intravenously and intermittently during op－eration in each groups. Bispectral index was maintained at 40-60. Blood samples were taken from radial artery and right atrial blood at 6 time points：after the induction of anesthesia（baseline，T1），before OLV（T2），at 30 min（T3），60 min（T4） after OLV，before the end of OLV（T5） and after operation（T6） to measure blood gases and to calculate Qs/Qt. Serum malondialdehyde（MDA） concen－trations and superoxide dismutase（SOD） activity were measured at T1，T3-T5. Results：Qs/Qt and MDA concentrations were significantly higher while PaO2、SOD activity were significantly lower during operation（from T3 to T5） compared with those at T1 in three groups（P<0.01）. Qs/Qt at T4 and MDA at T5 were significantly lower while SOD was significantly higher in SP group than in group P and group S（P<0.05）. Qs/Qt was significantly lower at T3 while was significantly higher at T5 in group S than in group P. There was no differ－ence in PaO2 among the three groups. Conclusions：Sevoflurane inhalation in advance before OLV could reduce intrapulmonary shunt and oxidative stress during OLV in patients undergoing esoph-ageal cancer resection.