The majority of haematological malignancies represent sporadic diseases, but hereditary entities with predisposing genetic alterations have also been described. Diseases of the myeloid and lymphoid cell lineages with genetic predispositions are associated with heterogeneous clinical manifestations, with many symptoms being specific for certain cytogenetic and molecular aberrations. Apart from the myeloid predisposition syndromes with clear Mendelian inheritance patterns, cases with ambiguous predisposing factors are also known, but their role in hereditary leukemogenesis is still poorly understood. The presence of these genetic lesions is usually associated with an increased risk of familial malignancies and often leads to familial disease aggregation. Lymphoid malignancies often lack the disease-associated germline pathogenic variants, with their propensity to familial aggregation being most likely explained by their complex genotype serving as a hereditary base to many sporadic diseases. The heterogeneous clinical features and the large number of potentially affected genes tend to make the diagnosis of hereditary haematological malignancies difficult, however the elevated familial risk caused by predisposing genetic alterations underlines the importance of testing for individuals and families with genetic susceptibility.