To evaluate an effect of acute ethanol pretreatment on the liver injury in toluene-treated rats, toluene(50% in olive oil) was intraperitoneally given four times at 0.3ml/100g body weight at interval of one day to the ethanol-pretreated rats(0.3ml of 50%/100g body weight). The increasing rate of liver weitht per body weight(%), serum levels of alanine aminotransferase (ALT) activity, liver lipid peroxide content was higher in toluene treated rats pretreated with ehtanol than those treated with toluene alone. Concomitantly the hepatic glucose-6-phosphatase activity was increased whereas glutathione content was decreased by ehtanol pretreatment before toluene administration in rats. In case of direct administration of acetaldhyde or benzaldehyde to the rats, the liver weitht per body weight(%) and serum levels of ALT activity were almost higher than the control group. There results indicate that the toluene treated rats showed the reversible injury of liver and intensified. however, by the ethanol treatment.