The purpose of this guideline is to maximise the safety of patients who need haemopoietic stem cell transplantation (HSCT) and make the best use of NHS resources, while protecting staff from infection. On , we updated the guideline to reflect changes to best practice and service organisation, which have been adapted over time thoroughout the pandemic. Follow the usual professional guidelines, standards and laws (including those on equalities, safeguarding, communication and mental capacity), as described in NICE's information on making decisions using NICE guidelines. This guideline is for: health and care practitioners; health and care staff involved in planning and delivering services; commissioners; donor registries. It covers HSCT in adults, children and young people. The recommendations bring together: existing national and international guidance and policies; advice from specialists working in the NHS from across the UK; these include people with expertise and experience of treating patients for the specific health conditions covered by the guidance during the COVID-19 pandemic. For advice on managing COVID-19 in children, young people and adults, see NICE's guideline on managing COVID-19. We developed this guideline using the interim process and methods for developing rapid guidelines on COVID-19 in response to the rapidly evolving situation.