The use of mTOR inhibitors in the field of haematology is very broad, varying from standardised first-line treatments (GvHD), to promising new drug regimens whose results are waiting to be confirmed in multicentre studies (autoimmune haemolytic anaemia, myelodysplasias, acute leukaemias, lymphomas, multiple myeloma, Waldenstrom macroglobulinemia, immune thrombocytopenic purpura, acquired aplastic anaemia, pure red cell aplasia, and autoimmune lymphoproliferative syndrome). Here, MTOR is linked to graft versus host disease.