Tetrachloroethylene in a concentration of 0.05 resp. 0.1 mg/kg bw/d was offered in drinking water to a group of NMRI-mice. Besides a decrease in bodyweight an increase in the relative weight of the spleen resp. of the kidneys could be determined. The liver and the brain remained uneffected. In the offered concentration, tetrachloroethylene influenced the lipoprotein metabolism in the liver in the sense of a chronic-alcohol-toxic liver change, whereas the liver cell was not destroyed in toto. The unchanged rate of the synthesis of liver cells could be established sufficiently through the normal serum-glutamate-pyruvate-transaminase, an unchanged serum electrophoresis as a measure for the efficiency of the protein synthesis of the liver cells, furthermore a swelling of the liver and/or an enlargement of the liver could not be diagnosed. The erythropoietic system was found to be most susceptible to tetrachloroethylene. We could detect a defect like in the case of hemolytic anemia, this manifested itself in a very high increase of the lactatdehydrogenase, in an increase of the LD-isoenzyme-1, as well as in the occurrence of reactive initial stages of erythrocytes in the bone marrow and in the moderate degree of a hyperchrome anemia in the peripheral blood-count.