Venous thromboembolism (VTE) and bleeding are serious complications of cancer and its treatment. A recent survey of UK paediatric haematologists and oncologists identified a broad variety of practice in the management of issues relating to these complications in children with leukaemia, reflecting significant areas of uncertainty (Biss et al, 2016a, 2017). The purpose of this guideline is to provide information and guidance on the management of these issues in children being treated for leukaemia and other forms of cancer.