It is well known that an excess or deficiency, as well as a metabolic disorder in trace elements, causes various disturbances in the body; and further that there are many metalloenzymes or metal-enzyme-complexes which contain these trace elements. In recent years with the advance in research methods, active attempts have been made to clarify the correlation between trace elements and those enzymes which require them as a cofactor. Regarding zinc and zinc metabolism, a review by Vallee (1) is well known among many reports from various workers. As to the correlation between zinc and carbonic anhydrase, Vallee et al. (2, 3) and Wolff (4) reported that in red blood cells, the zinc level is directly related to carbonic anhydrase activity and its content. In order to find a similar relation between ⁶⁵Zn metabolism and carbonic anhydrase activity in the liver, the authors have made several researches both in tumor-bearing animals (5-7) and animals with abnormal endocrine milieu (8-10), but failed to obtain any definitive conclusion. Many studies have been made on zinc metabolism under various diseases, especially in hepatic disorders (4, 11, 12). Baxter and Smith (13) reported that administration of carbon tetrachloride into rats made no change in ⁶⁵Zn uptake in their livers but decreased ⁵⁴Mn uptake; and Smith et al. (14) reported that ²⁸Mg uptake increased in similarly treated animals. Further, there have been many reports on change in iron metabolism and hepatic catalase activity in tumor-bearing animals. Also, the authors previously reported on the relation between ⁵⁹Fe metabolism and catalase activity in liver of Ehrlich ascites cancer bearing mice (15). Similar reports were made on liver-damaged animals (16-24). Concerning the other metal metabolism, Thiers and Vallee (25), Thiers et al. (26) and Reynolds et al. (27) reported that the administration of carbon tetrachloride results in striking increase of calcium and decrease of potassium content of the mitochondria of rat liver as compared with normal mitochondria, and that the sodium concentration is elevated in all fractions obtained from the liver sample taken at 16 hours after carbon tetrachloride administration, the magnesium concentration is increased in the supernatant fraction, the zinc and manganese concentrations in whole liver and the subcellular fractions are virtually stable throughout the period of marked changes in calcium and potassium contents, iron is altered, being elevated in both mitochondria and microsomes at 40 hours after carbon tetrachloride administration (26). The present experiment investigates the relation between ⁶⁵Zn metabolism and carbonic anhydrase activity and between ⁵⁹Fe metabolism and catalase activity in animals treated with carbon tetrachloride or ethionine to cause hepatic disorder.