Chronic lymphocytic leukemia (CLL) is the most common hematological malignancy in western countries. It is characterized by the accumulation of monoclonal CD5+ B-lymphocytes in blood, bone marrow, and lymphoid organs, due to an imbalance between proliferation and cell death. It is a complex disease that remains misunderstood. This book, therefore describes globally this very common but extremely complex type of leukemia. Throughout this book the principal biological hallmarks of B-cells are compared with the principal features of CLL-leukemic B-cells. Additionally the current CLL epidemiology...