One hundred years ago the word anemia was in use, although few measurements of blood had been performed. Purpura and plethora were classified, but there were few, if any, supporting laboratory studies. Blood cells were examined in the fresh state without staining, and blood cell counting was just beginning. Fifty years ago, reduced platelets were described in connection with purpura hemorrhagica, and the blood groups were discovered. A little over a quarter of a century ago, the effects of liver in pernicious anemia opened wide the newer hematology, in which pathophysiology was emphasized. At present we are at the beginning of the era of hematological chemistry. This will undoubtedly lead to expansion in the fields of coagulation disorders, immunohematology, and the hemoglobin abnormalities. The prevention of useless blood loss and the conservation of this most precious fluid for an increasingly healthy society must be the constant aim of the worldwide fraternity of hematologists.