Variations in the levels of ATP and triglyceride (TG) in the liver and TG concentration and GPT activity in the plasma of mice exposed to 1, 1, 1-and 1, 1, 2-trichloroethane (TCE) were studied. The decrease in liver ATP, increase in liver TG, decrease in plasma TG and increase in plasma GPT were greater in mice exposed to 1, 1, 2-TCE than in mice exposed to 1, 1, 1-TCE. It was inferred that the biosynthesis of serum lipoprotein in the liver was inhibited, thus causing fatty liver. The increased level in plasma GPT is considered to be a sensitive and early indication of liver disturbance caused by TCE. The decrease in liver ATP, and the increase in liver TG in the mice were in the desending order of carbon tetrachloride, 1, 1, 2, 2-tetrachloroethane, 1, 1, 2-TCE, tetrachloroethylene, trichloroethylene, 1, 1, 1, 2-tetrachloroethane, and 1, 1, 1-TCE. The inhibitory effect of 1, 1, 2-TCE on the liver was stroner than that of 1, 1, 1-TCE, suggesting that the effect of 1, 1, 2-TCE is due to production of free radicals.