Anemia is among the most frequently encountered pathologies in medical practice. In most cases the underlying cause is easily defined, as for example iron deficiency or vitamin B12 deficiency. However, cases with a more complex picture of anemia should also be recognised by the practitioner and referred within due time to the specialist. The aim of the present review is to provide the tools for a work-up of anemias which is at the same time rational as well as precise. A precise diagnosis is the prerequisite for an effective treatment of any given anemia. We strongly feel that no anemic patient should be treated by trial and error.