This book primarily focuses on the extensive topic of T-Cell Leukemia. The aim of this book is to present the readers with a descriptive overview of the scientific developments in T-cell malignancies and to shed light on the most important findings that will help the readers comprehend the basic mechanisms of T-cell leukemia as well as the future directions that are likely to lead to new therapies. For the assurance of an efficient approach to these problems, translational researchers, basic scientists and veteran clinicians from this field have contributed information in this book. Therefore, the target audience for this book consists of both clinicians who will employ this book as a means to comprehend rationales behind the formulation of new treatments for these diseases as well as basic scientists who will use this book as a review of the developments in molecular mechanisms of T-cell malignancies.