GVHD remains the major impediment to broader application of allogeneic haematopoietic SCT. It can be prevented completely, but at the expense of other complications, rejection, relapse or delayed immune reconstitution. No optimal prevention or treatment method has been defined. This is reflected by enormous heterogeneity in approaches in Europe. Retrospective comparisons between different policies, although warranted, do not give definite answers. In order to improve the present situation, an European Group for Blood and Marrow Transplantation and the European LeukemiaNet working group has developed in a Delphi-like approach recommendations for prophylaxis and treatment of GVHD in the most common allogeneic transplant setting, transplantation from an HLA-identical sibling or unrelated donor for standard risk malignant disease. The working group proposes these guidelines to be adopted as routine standard in transplantation centres and to be used as comparator in systematic studies evaluating the advantages and disadvantages of practices differing from these recommendations.