Solomons et al. studied the effect of the Fe-fortifying agent, NaFe-ethylenediaminetetraacetic acid (EDTA) upon Zn availability in man by measuring the change in plasma Zn concentration for 6 hr after administering a standard dose of 25 mg of Zn with several test materials. The work of F. A. Suso and H. M. Edwards showed improved utilization of only Zn and Mn with the addition of EDTA. After the recognition that the addition of chelating agents to a diet can improve the utilization of certain trace elements, it became of interest to know the levels at which they can be tolerated in the diet. P. Vohra and D. C. Bond fed various levels of EDTA to coturnix chicks in a basal diet of practical feedstuffs. Nitrilotriacetic acid (NTA) or an equimolar level of Na2-NTA caused a moderate decrease in the weight of the chicks, unrelated to the Ca of the diet.