The prevalence of anemia in old patients is 20%. Anemia is mostly multifactorial associated with multiple comorbidities that are frequently observed in people of 65 years or older. Chronic renal failure, inflammatory diseases, nutrient deficiencies and especially iron deficiency are the most associated conditions with anemia. Anemia represents a prognosis marker of general health in old people. Thus anemia is associated with higher rates of morbidities (such as unplanned hospitalizations) and greatest mortality. Therefore anemia could be considered either as a consequence of chronic diseases or a prognosis marker of their severity. The prognosis of chronic cardiac failure is for example worst in anemic patients. Finally anemia is listed as a component of the frailty.