The development of tyrosine kinase inhibitors (TKIs) has revolutionized the treatment of chronic myeloid leukemia (CML).1,2 However, despite effectively inducing remission and prolonging survival in patients with CML, TKI therapy does not eradicate leukemia stem cells (LSCs), which are responsible for drug resistance, relapse, and disease progression.2 Given recent changes to the treatment paradigm, updated clinical practice guidelines are essential to ensure optimal clinical care is provided.2 The British Society for Haematology (BSH) published a guideline update for the investigation and management of CML in adults and children in the British Journal of Haematology.1 Lead author of the guidelines, Graeme Smith, MD, of St Jamess University Hospital in the United Kingdom, and coauthors, developed the evidence-based recommendations to provide clinical practitioners with clear guidance on the diagnosis and treatment of adults and children with CML (Tables 1 and 2). Diagnosis and Key Investigations The diagnosis of CML is established based on findings from a peripheral blood smear and bone marrow aspirate showing positivity for BCR-ABL1, and the presence of the Philadelphia (Ph) chromosome. The Ph chromosome, or a variant, is present in approximately 95% of CML cases.