An elucidative account regarding the diagnosis, prevention and management of T-cell leukemia has been presented in this book. T-cell leukemia is a comparatively rare malignancy of thymocytes. Nearly 20 variants and entities of this disease are known to exist. Each one of them has distinct characteristics, like diagnosis, pathogenesis, prognosis, epidemiology and therapeutic approaches. Although it is a relatively rare malignancy, various types of T-cell leukemia still result in a poor prognosis due to their quick progression. Hence, growth in new preventive and therapeutic strategies is required for improving prognosis. The aim of this book is to present the readers with a descriptive study of the disease encompassing the basics of epidemiology, immunological features, pathogenesis and morphology. The book also emphasizes on the current achievements in fundamental and clinical researches including new therapies and molecular mechanisms of T-cell leukemia.