Iron deficiency (ID) is common in the pediatric population, primarily due to inadequate iron intake from food and a high requirement due to rapid growth. The most significant for pediatric practice are latent iron deficiency and iron deficiency anemia. Hyposiderosis significantly impacts a child's physical and cognitive development and immunological reactivity. It can be an independent condition and complicate the course of several other diseases. The article presents data on the most significant factors contributing to the ID, risk groups, clinical presentation features (sideropenic and anemic syndromes), criteria of laboratory diagnostics of iron deficiency anemia according to the clinical guidelines "Iron deficiency anemia" approved by the Russian Ministry of Health in 2021, and the latent iron deficiency developed by the World Health Organization experts. Also, the algorithm of ID primary prevention, diet therapy approaches, and the use of functional products and dietary supplements to meet the iron requirement of a child's organism are discussed.