The alleged role of metal ions in vitamin B_<12> absorption was studied in rat intestine by Okuda's loop method in which radioactive vitamin B_<12> and rat stomach extract or its purified fractions were employed. It was demonstrated that administration of ethylenediaminetetracetate drastically reduced intrinsic factor action on the absorption of small doses, whereas no such effect was obtained for the absorption of large doses. This absorption inhibiting effect was counteracted by Ca^<2+> and Mg^<2+> but not clearly by Zn^<2+>. EDTA exerted no direct effect on intrinsic factor activity when mixed in vitro and therefore must affect vitamin B_<12> absorption inside the gut.