INTRODUCTION: People dying in Britain spend, on average, 3 weeks of their last year of life in hospital. Hospital discharge presents an opportunity for secondary care clinicians to communicate to general practitioners (GPs) which patients may have a poor prognosis. This would allow GPs to prioritise these patients for Advance Care Planning.The objective of this study is to produce a critical overview of research on the communication of poor prognosis between secondary and primary care through a systematic review and narrative synthesis. METHODS AND ANALYSIS: We will search Medline, EMBASE, CINAHL and the Social Sciences Citation Index for all study types, published since 1 January 2000, and conduct reference-mining of systematic reviews and publications. Study quality will be assessed using the Mixed-Methods Appraisal Tool; a narrative synthesis will be undertaken to integrate and summarise findings. ETHICS AND DISSEMINATION: Approval by research ethics committee is not required since the review only includes published and publicly accessible data. Review findings will inform a qualitative study of the sharing of poor prognosis at hospital discharge. We will publish our findings in a peer-reviewed journal as per Preferred Reporting for Systematic review and Meta-analysis (PRISMA) 2020 guidance. PROSPERO REGISTRATION: CRD42021236087.