Background: Poor communication to GPs at hospital discharge threatens patient safety and continuity of care, with reliance on discharge summaries that are commonly written by the most junior doctors. Previous quality improvement efforts have largely focused on adherence to standardised templates, with limited success. A lack of understanding has been identified as a cause of the issue's resistance to decades of improvement work. Aim: To understand the system of communication to GPs at hospital discharge, with a view to identifying potential routes to improvement. Design & setting: A qualitative exploration of the secondary-to-primary care communication system surrounding a large UK hospital. Method: A systems approach, recently defined for the healthcare domain, was used to structure and thematically analyse interviews (n = 18) of clinical and administrative staff from both sides of the primary-secondary care interface, and a subsequent focus group. Results: The largely one-way communication system structure and the low level of hospital stakeholder insight into recipient GP needs emerged as consistent hindrances to system performance. More open lines of communication and shared records might enable greater collaboration to share feedback and resolve informational deficits. Teaching sessions and assessments for medical students and junior doctors led by GPs could help to instil the importance of detail and nuance when using standardised communication templates.