The role of copper in human nutrition remains obscure and the requirement is unknown. Studies in animals indicate that copper is necessary for the synthesis of the iron-porphyrin ring. In copper deficiency, the tissue content of cytochrome oxidase has been found to be markedly decreased. It has been shown that 2.0 mg. of copper daily will maintain balance in an adult. The diet usually furnishes 2.0 to 5.0 mg. and since copper is so widely distributed in foods, it seems likely that an adult would succumb to caloric inadequacy before severe depletion of copper could develop (17). The plasma concentration of copper is usually greater than 90 µg/100 ml. Although hypocupremia has been found in the newborn and in hepato-lenticular degeneration, tissue stores of copper are increased in both conditions. Hypocupremia and an in-creased excretion of copper have been found in the nephrotic syndrome but when an anemia was present, there was no hematopoietic response to copper (17). To date, no definite evidence of copper deficiency in man has been presented. Copper has not been shown to be of assistance in the treatment of hypochromic microcytic anemia in adults and only rarely is copper a limiting factor in blood formation in infants.