Colored complexes with chromium III, copper II, or cobalt III have been used for the photometric determination of small amounts of ethylenediamine-tetraacetate. Microgram amounts of EDTA have also been determined indirectly by photometric measurement of the excess of nickel, copper, or iron III not bound in the metal-EDTA complex. However, these methods are restricted as many ions interfere. During the study of the photometric determination of bismuth with Pyrocatechol Violet, it was noted that EDTA decolorizes the red-violet bismuth-Pyrocatechol Violet complex. This finding has now been extended to the photometric determination of EDTA.