The study assessed the effects of supplementary feeding over 180 consecutive days on iron status of infants and toddlers at six tea plantation in West Java, Indonesia. The design used was a clinical trial: two eohorts (i.e., 12 and 18 months old children) and three treatment groups (i.e., energy + micronutrient, micronutrient alone, and placebo) per cohort. Every day except Sunday, the infants attended day-care centers. Twenty four centers and 136 infants were selected. The infants were screened for weight and length and those meeting the criteria (i.e., < -1 SD of length-for-age, and between -1 and -2 SD of weight-for-length of the NCHS reference) were included. The experimental unit was the day-care centers (DCC), where each DCC was randomly assigned to one of the three treatment. As expected, groups of energy + micronutrient and micronutrient alone of the 12 months cohort experienced a significant upward shift in hemoglobin, ferritin and TS and a downward change in FEP, while the values for the group of placebo remain about the same as at base line. In the first 6 month of treatments, the ANOVA for each iron indicator yielded significant main effects of treatment (P < 0.01) and for Hb with (P = 0.059) on 12 months cohort. On the other hand, the main effects of treatment on hemoglobin, TS, ferritin and FEP were not significant for the 18 months cohort. In the second 6 months of treatments, the only significant of the treatment effect (P < 0.01) was in serum ferritin on 18-month cohort. Under these circumstances, energy has a positive role in improving iron stores. It is likely that the equilibrium of hemoglobin and each iron indicators were reached in 6 months of treatment except ferritin still continued to increase up to 12 month. The effects of treatment on the improvement of iron status was stronger in 12 months than in 18 months.