Graft-versus-host disease (GVHD) continues to be a major obstacle to the success of allogeneic bone marrow transplantation. Furthermore, several clinical strategies being employed at this time in the field of bone marrow transplantation have had an impact on GVHD. In addition to the usual division of topics such as pathophysiology, and acute and chronic GVHD, papers dealing with the impact on GVHD created by allogeneic peripheral blood cell transplantation, donor leukocyte infusions, and unrelated bone marrow transplantation are considered separately.