Technical Abstract: Iron absorption from infant formula is relatively low. Alpha-lactalbumin and casein-glycomacropeptide have been suggested to enhance mineral absorption. We therefore assessed the effect of alpha-lactalbumin and casein-glycomacropeptide on iron absorption from infant formula in healthy term infants. Thirty-one infants were randomly assigned to receive 1 of 3 formulas (4 mg iron/L, 13.1 g protein/L) from 4-8 wk to 6 mo of age: commercially available whey-predominant standard infant formula (standard formula), alpha-lactalbumin-enriched infant formula (alpha-LAC), or alpha-lactalbumin-enriched/casein-glycomacropeptide-reduced infant formula (alpha-LAC/RGMP). Nine breast-fed infants served as a reference. At 5.5 mo of age, (58)Fe was administered to all infants in a meal. Blood samples were collected 14 d later for iron absorption and iron status indices. Iron deficiency was defined as depleted iron stores, iron-deficient erythropoiesis, or iron deficiency anemia. Iron absorption (mean +/- SD) was 10.3 +/- 7.0% from standard formula, 8.6 +/- 3.8% from alpha-LAC, 9.2 +/- 6.5% from alpha-LAC/RGMP, and 12.9 +/- 6.5% from breast milk, with no difference between the formula groups (P = 0.79) or all groups (P = 0.44). In the formula-fed infants only, iron absorption was negatively correlated with serum ferritin (r = -0.49; P = 0.005) and was higher (P = 0.023) in iron-deficient infants (16.4 +/- 12.4%) compared with those with adequate iron status (8.6 +/- 4.4%). Our findings indicate that alpha-lactalbumin and casein-glycomacropeptide do not affect iron absorption from infant formula in infants. Low serum ferritin concentrations are correlated with increased iron absorption from infant formula.