Studies reviewing hospital records have raised concerns about the safety of healthcare internationally. We aim to complete comparable research in general practice to identify patient safety threats and preventable harms occurring in this setting. Using methods adapted from the seminal hospital-based studies, we will retrospectively review the general practice records of a random sample of patients of representative general practices to identify and describe adverse events caused by healthcare management, and estimate their incidence and consequences. Leveraging from technology developments since the methodology was first developed, we will triangulate methods using the UK NHS Trigger Tool and the electronic searches of prescribing records we developed in a previous HRC project. Given the size and importance to health of the primary care sector, there is considerable potential for this study to develop new understanding of patient safety issues in primary care and lead to new initiatives to protect patients from harm.