Mice were injected intraperitoneally with 1, 1, 1-and 1, 1, 2-trichloroethane (TCE), and the amounts of their metabolites exhaled from the lungs and excreted in the urine were measured. Exhalation from the lungs ended 7 hours after the injection. The ratio of the accumulated amount of 1, 1, 1-TCE to the amount of 1, 1, 1-TCE injected was 84.7% , and the ratio for 1, 1, 2-TCE was 9.8% . The accumulated amount of total trichloro-compounds in the urine of mice to the amount of 1, 1, 1-TCE injected was 1.07% , and that for 1, 1, 2-TCE was 0.15% . The total amount exhaled from the lungs and that excreted in the urine of mice injected with 1, 1, 1-TCE was greater than that of mice injected with 1, 1, 2-TCE.