Removal of iron from biologically important ligands by desferrioxamine (DF), in vitro, is exceedingly slow because of a kinetic barrier. This kinetic barrier can be overcome by a variety of a small molecular weight anions, of which nitrilotriacetate (NTA) is a prototype. We explored the effect of NTA on DF iron mobilization in vivo. Iron mobilization was increased and the effect was synergistic.