Anemias are a numerous and diverse group of disorders, ranging from limited erythroid precursor production to premature senescence of RBCs. In many cases, anemia is associated with hypoproliferative erythropoiesis (HE), while in other forms, with ineffective erythropoiesis (IE). HE leads to a reduction of the erythron and consequent anemia by absent or limited proliferation of the erythroid precursors. In contrast, the anemia in IE occurs despite expansion of the erythron. In some cases, IE is triggered by impaired maturation of the erythroid precursors while, in others, by hemolysis and/or premature senescence of RBCs. In some forms of hypoproliferative anemia, administration of iron and an erythropoiesis-stimulating agent (ESA), such as recombinant human erythropoietin (rhEPO), might be required. In aplastic and IE-associated anemias, blood transfusion and iron chelation may be necessary as supportive therapies.