Donor lymphocyte infusion (DLI) prevents acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS) relapses following hematopoietic stem cell transplantation. Given the life-threatening toxicities such as graft versus host disease (GVHD), the identification of variables associated with response without toxicities is warranted. We hypothesized that HLA evolutionary divergence (HED), defined by the diversity between two given alleles of the same HLA gene, may be such a factor. A retrospective multicenter case-control study was conducted to evaluate the outcomes of pre-emptive (preDLI) and prophylactic DLI (proDLI) regarding their HED score, in AML or MDS patients. DLI-treated patients were matched with controls (1:2 matched) from French transplantation centers according to hospital, hemopathy, donor type, and risk classification. In total, 201 patients were included (