Despite a sharp decline in the prevalence of iron deficiency anemia (IDA) during the past several decades owing to better nutrition and iron-fortified foods, IDA continues to remain the most common disorder in the world. From about 4 months of age, iron stores are insufficient to maintain the rapidly expanding blood volume associated with normal growth. If there is no steady dietary supply, iron stores become depleted and IDA develops. It is known that iron deficiency (ID) may impair not only physical activity but also mental functions such as learning. Children with ID are found to have more psychomotor deficits and achieve lower scores in aptitude tests than those with normal iron status. Therefore, the detection and treatment, or preferably prevention of ID and IDA is imperative during late infancy, when increased vulnerability to ID coincides with the rapid growth and differentiation of the brain. The diagnosis of IDA is confirmed by the findings of a hemoglobin level <11 g/dL and low iron stores (serum ferritin level <12 microg/L, transferrin saturation <16%). Iron status should be evaluated in children who have risk factors for IDA such as low birth weight, premature baby, exclusive breastfeeding beyond 6 months of life, and weaning to whole milk and complementary foods without iron-fortified foods. With the management of underlying cause, oral iron therapy should be given to replenish iron stores. Parenteral therapy may be used in children who cannot tolerate or absorb oral preparations.