Much of the attention presently paid to leukemia is the result of recent progress in understanding and treatment. Chemotherapy of leukemia started in the late 1940s, and combination therapy evolved in the late 1950s. It was at that time that the clonality of leukemia was realized, after the discovery of chromosomal and then biochemical and immunological markers. And now we have the new data on retroviral and cellular oncogenes and the reports on human T -cell lymphoma/ leukemia viruses. Many more steps forward could be enumerated in a field which is so rapidly making the hematological textbooks outdated. In this volume, thirteen in-depth reviews from large multicenter trials in the Federal Republic of Germany summarize the current state of diagnosis and management of leukemias. Childhood ALL and AML adult ALL and AUL were investigated. While cure appears to be achievable for more and more patients with acute leukemia, we still pursue the aim of optimal palliation in chronic leukemias. The management of patients with leukemia therefore varies to a large extent in aggressiveness of therapy. In some situations, rescue from an otherwise lethal disease is provided by bone marrow transplanta tion, which is discussed in two chapters.