SummaryBleeding and thrombosis are not infrequent problems in children receiving treatment for acute lymphoblastic leukaemia (ALL). The exact frequency varies with age, co‐morbidity and treatment schedule, but the risk is highest in the first few weeks of treatment when disease and treatment‐related haemostatic abnormalities prevail. Recommendations for prevention and management are lacking due to a weak evidence base, resulting in considerable variation in practice. This article describes our personal practice in this area with reference to the available literature on the subject.