BACKGROUND: The communication of poor prognosis from secondary to primary care helps to ensure that patients with life-limiting illness receive appropriate coordinated care in line with their preferences. However, little is known about this information-sharing process. AIM: To determine how poor prognosis is communicated from secondary care to primary care. DESIGN AND SETTING: This was an international systematic review and narrative synthesis of studies published in English. METHOD: Four electronic databases were searched from 1 January 2000 to 17 May 2021, supplemented by hand-searching of key journals. One-quarter of titles and abstracts were independently screened by a second reviewer. Two reviewers undertook data extraction and quality appraisal, independently using the Mixed Methods Appraisal Tool. Data were analysed using narrative synthesis. Reporting follows Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidance. RESULTS: Searches identified 23 853 unique studies of which 30 met the inclusion criteria. Few studies had a focus on the interprofessional communication of poor prognosis. Information about prognosis was not commonly communicated from secondary to primary care and was more likely to occur if death was imminent. Lack of identification of poor prognosis by secondary care teams was a barrier. Facilitators included shared electronic records and direct clinician-clinician contact. GPs welcomed this information from secondary care and felt it was vital for continuity of care. CONCLUSION: Although the communication of poor prognosis from secondary to primary care is highly valued it is rare and associated with cultural and systemic challenges. Further research is necessary to understand the information needs of GPs and to explore the challenges facing secondary care clinicians initiating this communication.