Abstract Bioavailability of iron in soybean hull was investigated by hemoglobin regeneration efficiency (HRE), body iron status and maze test in rat pups with iron-deficiency anemia (IDA) induced by iron deficiency of dams during gestation or lactation (GID or LID group, respectively) and normal pups (N group). The soybean hull repletion diet (SH) and purified control diet (PC) as the experimental diets contained the same amount of iron (35mg/kg diet) and the pups in each group were divided into two subgroups by diet sources. The normal (N-SH), gestation iron deficiency (GID-SH), lactation iron deficiency (LID-SH) groups fed SH were significantly higher in food intake and growth than each of their respective control groups (N-PC, GID-PC, LID-PC) fed PC. After the feeding, hemoglobin concentrations approached normal value in all groups, but HRE were significantly higher with SH irrespective of iron deficient period. IDA rats in either lactation or gestation, when compared to normal rats, resulted in lower serum iron and transferrin saturation. Iron concentrations in both liver and spleen were significantly lower in LID-PC group than LID-SH and N-PC groups. The maze test showed a learning defect in either LID group, but GID groups were not significantly different in comparison with N groups. These results suggest that IDA in lactation may influence more serious growth and development than those in gestation, soybean hull iron has the higher bioavailability in normal and IDA-induced rats, and thus soybean hull is effective as source of iron supplement.