Hereditary hematological malignancies syndromes (HHMS) are still underdiagnosed. Yet, it proves essential to correctly identify these disorders in order to select the most appropriate conditioning regimen before transplantation and exclude an inherited mutation in sibling donors, while ensuring personal and familial counseling. We retrospectively reviewed 252 patients from 117 families with a personal or familial history of multiple cancers, including at least one hematological malignancy. A familial mutation was identified in eight families (GATA2, TERT, FANCA, TP53, PTCH1, BRCA1 and ATM), resulting in specific management and familial screening. This study highlights the necessity of early HHMS diagnosis through a close collaboration between hematologists and geneticists. To finish, we present recommendations to better diagnose and manage HHMS on the basis of our observations and the literature.