Hemotherapy is the medical specialty that obtains and administers blood as a treatment for various health conditions. The activities of this segment are comprised of blood banks, transfusion agencies, blood centers and services that work with stem cells and their ramifications (such as bone marrow transplants). Transfusion medicine has evolved from empirical blood administration to an evidence-based clinical discipline. Some factors contributed to the evolution observed in this area: the discovery of blood group antigens and the understanding of the host’s immune response to such antigens; the development of anticoagulation and blood storage methods; the creation of plastic bags that enable sterile fractionation of whole blood into its components; the evolution of automation and computing; the emergence of AIDS; the growing development of molecular genetics and biotechnology, the advent of Cell Therapy, and the emergence of Quality systems.