The effect of Lactobacillus acidophilus on iron bioavailability in rats was examined by the hemoglobin regeneration method. For hemoglobin depletion, female Wistar rats were fed an iron-deficient diet at 3 weeks of age for 13 days. Rats were then assigned to one of four groups, such that average blood hemoglobin value and average body weight were similar among the groups. For hemoglobin regeneration, they were fed one of two ferrous sulfate-supplemented diets that contained the following iron levels (mg/kg): 13.7 for two groups; 21.7 for the other two groups. In the two groups fed the same diet, one group additionally received oral administration of 2 ml of skim milk fortified with 0.3% yeast extract once or twice a day for 7 days, and other rats were administered with skim milk fermented by L. acidophilus SBT 2062 in the same manner. Hemoglobin regeneration efficiency (HRE) was significantly higher in the fermented product-given rats than in the skim milk-supplied rats. There was no significant interaction in HRE between the dietary iron group and the oral administration group. These results indicate that L. acidophilus SBT 2062 is effective for increasing of iron bioavailability in rats.