Iron deficiency and iron deficiency anemias are very common disturbances of the hematopoiesis. Although symptomatology and therapeutic possibilities are well known, one should keep in mind that iron deficiency is a symptom and not a diagnosis. The causes of iron deficiency are iron loss, malabsorption and insufficient supply. The best therapy is peroral treatment with well absorbable preparations, whereby the bioavailability has to be taken into consideration. Only in few cases a parenteral therapy which has more side effects is necessary. A overview about the possible therapy is given.