An atomic absorption Spectrophotometric (AAS) method for determining chelated iron in iron chelate concentrates was collaboratively studied by 13 laboratories. Nonchelated iron was selectively precipitated as ferric hydroxide from an aqueous solution of the sample by adjusting to pH 8.5 with sodium hydroxide. A filtered portion of the sample solution was diluted with 0.5N HC1, and the iron was determined by AAS using standards containing disodium EDTA. Six pairs of iron chelate materials (12 samples) were analyzed and the average coefficients of variation were iron EDTA 3.52%, iron HEDTA 4.16%, iron DTPA 3.55%, iron EDDHA 3.52%, iron citrate 2.86%, and iron DPS 8.47%. The method has been adopted official first action.