A method for the isolation in high yield of the iron storage protein ferritin has been developed which has reduced to a minimum the chance of discriminating against either low iron or high iron ferritin. The procedure has "been applied to the study of ferritin metabolism in the livers of male and female rats during five weeks of protein deprivation. With males more ferritin iron was found in the livers of the protein deficient animals than the protein replete controls which was in accord with earlier work of other investigators. With females no difference in ferritin iron was observed between protein deficient and control animals. Both protein deficient males and females stored ferritin protein to approximately similar levels as those of the controls. Protein deficient males increased the average number of iron atoms per molecule of protein significantly above that of their protein replete counterparts, whereas the average iron content for protein deficient and normal females was similar. The average iron content of protein deficient males approached that of the females, A close relationship between liver ferritin iron and protein has been shown which substantiates other previously reported evidence for a sex difference in iron storage. Moreover it has been shown that in protein deficiency iron storage in the male closely resembles that of the female. A method for the isolation in high yield of the iron storage protein ferritin has been developed which has reduced to a minimum the chance of discriminating against either low iron or high iron ferritin. The procedure has been applied to the study of ferritin metabolism in the livers of male and female rats during five weeks of protein deprivation. With males more ferritin iron was found in the livers of the protein deficient animals than the protein replete controls which was in accord with earlier work of other investigators. With females no difference in ferritin iron was observed between protein deficient and control animals. Both protein deficient males and females stored ferritin protein to approximately similar levels as those of the controls. Protein deficient males increased the average number of iron atoms per molecule of protein significantly above that of their protein replete counterparts, whereas the average iron content for protein deficient and normal females was similar. The average iron content of protein deficient males approached that of the females. A close relationship between liver ferritin iron and protein has been shown which substantiates other previously reported evidence for a sex difference in iron storage. Moreover it has been shown that in protein deficiency iron storage in the male closely resembles that of the female.