Blood and Marrow Transplantation (BMT) has evolved over the past 20 years into a successful therapy for a variety of malignant and non-malignant diseases. BMT allows for safer use of very high doses of radiotherapy and/or combination chemotherapy and can also allow for immunomodulation. The bone marrow -- the sponge-like tissue found in the centre of certain bones-contains stem cells that are the precursors of white blood cells, red blood cells, and platelets. These blood cells are vital for normal body functions, such as oxygen transport, defence against infection and disease, and clotting. Blood cells have a limited lifespan and are constantly being replaced; therefore, healthy stem cells are vital. In association with certain diseases, stem cells may produce too many, too few, or otherwise abnormal blood cells. Also, medical treatments may destroy stem cells or alter blood cell production. The resultant blood cell abnormalities can be life threatening. Bone marrow transplantation involves extracting bone marrow containing normal stem cells from a healthy donor, and transferring it to a recipient whose body cannot manufacture proper quantities of normal blood cells. The goal of the transplant is to rebuild the recipient's blood cells and immune system and hopefully cure the underlying ailment. This book presents the latest research in this rapidly-growing field.