The effect of natural and synthetic chelators on iron (59Fe) absorption in mice has been studied in three different experiments using single or repeated intragastric administrations of chelator iron (59Fe) complexes of different chelator doses. The amount of 59Fe in whole animals, their excretions and also distribution of 59Fe in blood, liver, spleen and heart was measured at one, three and eight weeks following the 59Fe-chelator administrations and compared to controls which received the same amount of iron (59Fe) but no chelator. 2-Hydroxy-4-methoxypyridine-1-oxide and maltol, which form lipophilic iron complexes, were found to cause an increase of 59Fe absorption while other chelators caused a decrease either by precipitating iron eg. 2-hydroxypyridine-1-oxide or by forming non absorbable soluble iron complexes eg. desferrioxamine, mimosine, EDTA. 1,2-Dimethyl-3-hydroxypyrid-4-one caused a decrease in iron absorption at a high dose (10 mg) by comparison to the control group but it did not significantly alter iron absorption at a lower dose (2 mg). It is suggested that natural and synthetic iron chelating compounds influence the absorption of iron and some may have a use in the treatment of diseases associated with gastro-intestinal iron absorption imbalance.