While the modern era of leukemia chemotherapy began recently,the recognition of leukemias has been mainly recorded in the second part of the nineteenth century.This brief historic review reports the first descriptions of the disease and the major advances in its history from its roots to the beginning of the twentieth century.Although most treatments for leukemia were ineffective until the middle of the twentieth century,it seemed of interest to review some pertinent exemples of the evolution in the knowledge of this disease(relied upon chronology as an organizing framework,while stressing the importance of themes),since our current knowledge about leukemia is still mainly based on the first accounts of scientific and medical discovery.Early in the nineteenth century,a small number of cases of patients with uncommon or peculiar alterations of the blood were published.Of the cases,four might suggest symptoms of chronic leukemia.The first published case was the detailed report prepared by John Hughes Bennett in the“Edinburgh Medical and Surgical Journal”October 1845.Leukemia gradually became accepted as a distinct disease and published case reports grew in number.Concomitantly,clinical and pathological description of the disease became more detailed.