Allogeneic bone marrow transplantation (BMT) is being used increasingly to treat diverse diseases in Japan. The distinctive aspects of allogeneic BMT in Japan include the lower incidence of acute graft-versus-host disease, which may be attributable to less disparity in histocompatibility antigens in Japanese. Research in the field of allogeneic BMT in Japan has covered the use of recombinant hemopoietic growth factors, especially granulocyte colony-stimulating factor, and novel immunosuppressive agents.