The factors regulating concentrations of iron and iron-binding proteins in milk are incompletely known. Since anemic women usually are given iron supplements, we have evaluated the effect of this practice on iron and lactoferrin levels in milk. Lactating Peruvian mothers (n = 29) were studied during the first month of lactation. Lactoferrin and iron in milk were analyzed at 2 and 30 days post-partum. Mothers who were anemic (Hgb < 110 g/L) (n = 19) received iron treatment starting from the second day after delivery. Hemoglobin concentrations improved in the treated group from a mean of 92 g/L to 105 g/L and hematocrit from 28.2% to 32.6% (p < 0.05). Iron concentration in milk from anemic mothers was 0.90 and 0.38 mg/L at 2 and 30 days post-partum. In the non-anemic group, iron concentration was 0.80 and 0.35 mg/ml. The concentration of lactoferrin in milk from the anemic group was 6.75 mg/ml and 3.67 mg/ml analyzed at the 2nd and 30th day of lactation, respectively, and for the non-anemic group 5.34 mg/mL and 4.34 mg/ml. Milk iron values were within the range previously reported for healthy mothers. Thus, anemia did not affect milk iron or lactoferrin concentrations (day 2). Treatment with iron improved iron status of the anemic women but did not affect iron or lactoferrin levels in their milk (day 30). © 1995.