The improvement of molecular biology techniques and human genome mapping and sequencing boosted the molecular analysis of chromosomal abnormalities observed in human hematological malignancies. The characterization of structural abnormalities (translocation, deletion) has proven particularly seminal. A better understanding of the pathology itself and of its generation arose from the identification of the genes involved in the chromosomal translocations of human leukemia. This work summaries some of the present knowledge regarding human leukemogenesis.