There are three periods of the history of the epidemiology of leukemias. The first period is characterized by 3 features: the description of the occupational leukemias (radiations, benzene) with more recently the war leukemias (Hiroshima), the leukemia induced by chemotherapy; the description of the leukemias of animals induced by viruses (chicken, mice and more over cats); and the concept of the geographical hematology. The second period may be called "Burkitt period" so important are the consequences of the discoveries made in Uganda. The third period is Japanese and American with the leukemias induced by the virus HTLV 1 and the recent extensions. Such is the past. The present is defined by strong data (diversity of causes, diversity of the combinations of causes, of the etiologic pluralism), and by persisting weaknesses (epidemiology, classification of leukemias). Three ways for the future: induction, prediction, and correlation with the hope of an efficient prevention.