【Abstract】Objective To investigate the effects of pretreatment with etomidate on hepatic injury and the contents of alanine transaminase (ALT), aspartate transaminase( AST) in plasma and malondialdehyde (MDA), superoxide dismutase (SOD) in hepatic tissue during hepatic ischemia reperfusion injury (HIRI) in dogs. Methods 20 adult healthy hybrid canines were randomly divided into 4 groups(n=5): Sham group(S), Ischemia reperfusion group (I/R), low dosage of Etomidate group(E1, 0.6 mg/kg) and high dosage of Etomidate group(E2,1.5 mg/kg.Canines in all groups were injected Etomidate or NS except Sham group. The porta hepatis of canines in sham group was separated without ligation. The model of HIRI were established by ligating porta hepatis.The biochemical indicators of ALT and AST in plasma were measured at four time points: before blocked,30min after ischemis, 1,2 h after reperfusion. The contents of MDA and activity of SOD in hepatic tissue were also measured. Hepatic tissue was observed with light microscope after operation. Results Compared with group S, group I/R, group E1 and group E2 increased the expression level of ALT and AST in plasma(P<0.01). Compared with group I/R, the level of ALT, AST in group E1 and group E2 decreased significantly the expression level of ALT, AST in plasma(P<0.01), and group E2 more obviously[Reperfusion 2h: ALT: (2 911±89) U/L(I/R), (863±95) U/L(E2); AST: (2 722±103) U/L(I/R), (1056±115) U/L(E2)]. Compared with group S, group I/R, group E1 and group E2 increased the expression level of MDA and group I/R decreased the expression level of SOD, group E1 and group E2 increased the expression level of SOD in hepatic tissue(P<0.01). Compared with group I/R, group E1 and group E2 decreased significantly the expression level of MDA and increased significantly the expression level of SOD in hepatic tissue(P<0.01), and group E2 more obviously[MDA: (21.70±2.01) nmol•mg-1•prot-1 (I/R), (12.69±1.02) nmol•mg-1•prot-1 (E2), SOD: (191±12) nmol•mg-1•prot-1(I/R), (634±26) nmol•mg-1•prot-1(E2)]. Light microscope showed evidently that the pathological changes of hepatic tissue were more slight in group E1 and group E2 than in group I/R, and group E2 more slight than group E1. Conclusions Pretreatment with etomidate has protective effects on hepatic ischemia reperfusion injury, and it is related to the control lipid peroxidation of etomidate. And the protective function of etomidate large dosage group(1.5 mg/kg) was more reliable.