Purification by the gel-filtrations with Sephadex G-15 and G-50 was performed on a Fe(III)-lactose complex preparation containing free sugars with their derivatives. The most desirable result was obtained with a bicarbonate buffer solution (pH 9.5, µ = 0.1) as the eluent. The purified Fe(III)-lactose complex was composed of Fe and sugar in the molar ratio of 1, and was a polymer of molecular weight 5,000～10,000. The structure of the polymer was probably similar to that proposed by SPIRO et al. The molecular weight of the polymer is very small compared to the molecular weight (250,000) of the Fe(III)-hydroxopolymer formed in alkaline solutions. Accordingly, the addition of sugars in Fe(III) solutions brings about the considerable inhibition of the polymerization of Fe-hydroxo-ions and makes the passive transport of Fe through the intestinal wall possible.