A previous study resulted in the discovery of a unique, undesignated strain of mice, referred to as SM (Super Mouse), whose progeny exhibited a resistance to dietary zinc deficiency when pups from the strain suckled dams fed a zinc-deficient diet. Examination of the zinc metabolism in these mice demonstrated in the study reported here that SM mice accumulated significantly more zinc during in utero development than do mice of other strains. Adult mice of the SM strain contained significantly more bone zinc than did mice of other strains. Adult SM mice excreted significantly less 65Zn than did mice of other strains when the mice were fed a zinc-deficient diet. These observations suggest that SM mice are able to resist periods of zinc-deficiency as a result of the development of highly efficient systems for storing and reabsorbing zinc.