Iron deficiency is the most prevalent nutrition deficiency among infants and young children in industrialized as well as developing countries. It is a condition that is preventable through appropriate dietary measures. The infant born at term is endowed with a sizable amount of iron, which allows the infant to be fed a nearly iron-free diet (e.g., breast milk) for 4-6 months without becoming overtly iron deficient. This has led some to conclude that depletion of iron stores in healthy infants is a normal and, hence, innocuous process that usually gives way to gradual repletion of iron stores as dietary diversification leads to greater iron intakes. Preservation of maternal iron stores at the expense of infant iron stores may have offered survival advantages to the human species during evolution. But there is no evidence that depletion of iron stores can offer advantages to infants in industrialized or developing countries. On the contrary, there is ample documentation of shortterm as well as long-term adverse effects from iron deficiency. Prudence therefore dictates that a high priority be assigned to the prevention of iron depletion and deficiency among infants and young children worldwide.