The purpose of this guideline is to maximise the safety of patients who need radiotherapy and make the best use of NHS resources, while protecting staff from infection. It will also enable services to match the capacity for radiotherapy to patient needs if services become limited because of the COVID-19 pandemic. We added 3 recommendations for research following a review of the evidence on the effects of systemic anticancer treatment or radiotherapy on the risk of severe illness or death in patients with cancer and COVID-19. NICE has also produced a COVID-19 rapid guideline on delivery of systemic anticancer treatments. This guideline focuses on what you need to stop or start doing during the pandemic. Follow the usual professional guidelines, standards and laws (including those on equalities, safeguarding, communication and mental capacity), as described in making decisions using NICE guidelines. This guideline is for: health and care practitioners; health and care staff involved in planning and delivering services; commissioners. 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 current COVID-19 pandemic. We developed this guideline using the interim process and methods for developing rapid guidelines on COVID-19 in response to the rapidly evolving situation. We will review and update the recommendations as the knowledge base develops using the interim process and methods for guidelines developed in response to health and social care emergencies.