CSF3 and chronic graft versus host disease: Although most previous studies did not show an association between G‐CSF administration and incidences of acute and chronic GVHD,1, 2, 3, 4, 5, 8, 10, 12 several studies demonstrated that administration of G‐CSF was associated with an increased risk of acute6, 7, 9 and chronic GVHD7, 9, 13 following BMT or PBSCT.