Iron deficiency is the most common micronutrient deficiency in the world. Children, particularly infants living in developing countries are highly vulnerable to infectious diseases. Therefore, understanding the relationship between iron deficiency and infection is of great importance. Iron deficiency is associated with impairment of innate (natural) immunity and cell mediated immunity, thereby contributing to increased risk of infections. The iron acquisition by the microbes and their virulence is determined by various host and microbial mechanisms. Altering these mechanisms might provide modes of future therapy for infectious diseases.