This book summarizes current knowledge on chronic lymphocytic leukemia (CLL), taking into account the most recent research. All aspects are considered, including pathophysiology, clinical presentation, diagnosis, prognosis, treatment, follow-up, and complications and their management. Readers will find important information on the various prognostic markers as well as practical guidance on the use of different diagnostic procedures. A key focus of the book is the changing treatment paradigm in CLL as progress in understanding of pathogenesis and pathophysiology leads to the identification of new potential therapeutic targets. General treatment concepts are clearly described, and it is explained how choice of treatment for CLL depends on stage, age, and performance status as well as specific genetic aberrations. In addition, frontline therapeutic strategies for disease relapse, including allogeneic stem cell transplantation, are reported. Looking beyond CLL, the diagnosis and therapy of T-cell prolymphocytic leukemia and T-cell large granular lymphocyte leukemia, two rare CLL-related entities, are addressed.