Male Sprague~Dawley rats were pretreated with phenobarbital and randomly divided into 6 groups and were exposed to O2,/N2/l. 2 MAC anesthetics for I hr; NC, 21 % O2/79% N2; HC, 14 %O2,/86%N2; NH, 21 %O2/79% N2/l. 2 MAC halothane;HH, 14 %O2/86 %N2/ 1. 2 MAC Halothane; NS, 21 %O2/79%N2/ 1. 2 MAC sevoflurane; HS, 14 %O2/86 %N2/ 1. 2 MAC sevoflurnae. Liver specimens andblood were taken 24 hrs after exposure. Thenecrosls and denaturatlon of hepatocellularwere quantltatlvely estlmated by stereoscopy.Ultrastructural morphology was analysed by computer. The liver ofall rats given halothane (14%O2) had extensive centrilobu- lar necrosls and denaltlration. There were an increase in serum glutamic pyruvic transmi- nase accompnaying the morphologic damage。No marked hepatotoxicity was foundin the rats following sevoflurane expoure compared with controls. Hypoxia was the main cause of swelling of mltochondria. Results suggest that sevoflurane has less hepattc injtry than holotnane.