The aim of the study was to know influences of estrogen and testosterone on carbon tetrachloride-induced liver damage in male Wistar rats. One hundred and two rats were divided into following six groups on the basis of the treatment: olive oil as control (O), carbon tetrachloride (0.1 ml/100 g, C), estradiol benzoate (0.1 mg/100 g, E), testosterone propionate (5 mg/100 g, T), C + E and C + T, in which each drug was intraperitoneally injected twice per week for consecutive 12 weeks. In the C + E group, decreases in serum albumin level at the 4th week and total cholesterol level at the 8th week seemed to be suppressed. And fibrotic change and fatty change were weak on the histological observation. However, hepatocellular hyperplasia was observed in 40% cases after the 8th week. On the flow cytometry analysis of the liver at the 4th week, an enhancement of hepatocellular proliferation was shown. Survival rate of the C + E group rats was lower than C group rats. On the other hand, in the C + T group, liver injury occurred in the same grade as C group, and the survival rate was worst among all six groups. These results suggest that simultaneous administration of estrogen with carbon tetrachloride could reduce hepatic injury, though it might cause hepatocellular hyperplasia.