Li-Fraumeni syndrome (LFS) is a rare cancer predisposing condition caused by germline mutations in TP53, the gene encoding the TP53 transcription factor. LFS is typified by the development of a wide spectrum of childhood and adult-onset malignancies, which includes, among others, the lymphoid and myeloid leukaemias, myelodysplastic syndrome and, to a lesser extent, lymphoma. Accordingly, it is important that haematologists/oncologists be familiar with this pleiotropic hereditary cancer syndrome. The high cancer risk and variability in type and age of cancer onset have raised questions about the underlying biology and optimal treatment approaches for individuals with LFS. Since its description almost 50 years ago, many clinical and basic research investigations have provided insights into the pathogenesis, manifestations, genetic testing and management strategies for individuals with LFS. Here we provide an update on the current state of knowledge regarding LFS with an emphasis, where possible, on information relevant to practicing haematologists.