Introduction: In childhood and adolescence, we often experience anemia due to iron deficiency, which is usually associated with insufficient dietary iron intake with increased growth needs. The consequences of anemia cause not only physical, but also cognitive and socioemotional problems. Purpose: The purpose of the diploma work is to present the negative effects of iron deficiency on the cognitive functions of children and to develop them. We wanted to highlight the impact on behavior, speech, sound perception, educational success and social problems. Methods of work: A descriptive working method was used with a review of original scientific and transparent scientific articles over a period from 2001 to 2018. The review took place from December 2018 to May 2019. Literature has been sought after various databases such as: CINAHL, Science Direct, Science Research and PubMed. The diploma thesis includes 42 scientific articles in Slovene, English and Russian, 11 of which are used for the presentation of results. Results: Research results suggest that anemia reduces children's cognitive skills, speech development, school success, impaired mental development, negatively affects memory and orientation in the environment, reduces attention and motivation in games, worsens orientation, commitment, responsiveness to people and stimuli, causes slowness, reduces activity, increases fear and uncertainty. In adolescents, it is associated with risky behavior, problematic behavior, friendship rejection, risky and early sexual intercourse, poorer emotion regulation, and more frequent symptoms of slow cognitive response. Adolescents with iron deficiency anemia show a more excessive and problematic use of alcohol and more often violate the rules and use dangerous substances. Discussion and conclusion: Iron deficiency is an important problem of public health around the world. The most exposed are pregnant women, infants aged 6 to 24 months, pre-school children, especially in developing countries and teenagers. Anemia in childhood can become a serious, long-lasting problem, which has irreversible effects on the cognitive development of a child. It is important to design a single integrated system for the early detection, treatment and prevention of iron deficiency anemia.