In this book we have set out to provide a practical guide to bone marrow diagnosis, based on an integrated assessment of peripheral blood and bone marrow aspirate films, trephine biopsy sections and supplementary investigations. We believe that a trephine biopsy specimen should not be examined and interpreted in isolation. We have therefore discussed the clinical context of bone marrow diagnosis and have given equal weight to cytological and histological features. Since bone marrow diagnosis is no longer based on morphological features alone, we have also discussed in detail the role of immunophenotypic, cytogenetic and molecular genetic analysis. We have incorporated the diagnostic criteria and terminology of the 2016 World Health Organization classification of tumours of haematopoietic and lymphoid tissues. We have dealt very fully with haematological disorders for which bone marrow examination is commonly performed. However, we have also sought to be comprehensive, including information on uncommon and rare disorders so that the book will serve as a useful reference source. When possible, we have illustrated rare as well as common conditions and have cited the relevant scientific literature extensively. As in the previous edition, magnifications are given as the microscopic objective used rather than the magnification on the printed page. Unless otherwise specified, trephine biopsy sections were embedded in paraffin wax. We have retained and expanded problems and pitfalls, diagnostic algorithms and summary boxes. We hope that haematologists, histopathologists and haematopathologists will continue to find Bone Marrow Pathology a useful aid in their day‐to‐day practice and that trainees in these disciplines will find it indispensable. Cytogeneticists, molecular geneticists and scientists working in flow cytometry laboratories should find that it provides them with a context in which to interpret their findings.