Great variations exist in the prophylaxis and treatment of GVHD in children undergoing allogeneic stem cell transplantation (SCT). The EBMT Working Party Paediatric Diseases (EBMT-WP PD) and the International BFM Study Group--Subcommittee Bone Marrow Transplantation (IBFM-SG), aimed at evaluating current local standards in the prevention and treatment of GVHD and steps which can be taken to achieve a uniform policy for the individual methods. Several conferences with their members assessed practices which are mainly applied or under investigation in children and identified where additional information is needed. For prevention of GVHD, the majority of the paediatric centres prefer CsA +/- MTX. Addition of folinic acid to MTX was considered for reduction of side-effects. During treatment of acute GVHD most centres administer prednisolone and whole blood level-adjusted CsA as medications of first choice. In cases of poor or no response to this therapy, additional immunosuppressive agents such as ATG, mycophenolate-mofetile and tacrolimus are being increasingly used. The treatment of chronic GVHD usually consists of various combinations of prednisolone and CsA. In severe cases, extracorporeal photopheresis, psoralene-UVA (PUVA) and thalidomide are administered.