Background: Clinical handover and obtaining best possible medication histories (BPMH) at transition points in care are key patient safety priorities. This study aimed to determine the accuracy of medication histories documented on general practitioner (GP) referral letters for patients referred to emergency departments. Methods: This was a multicentre prospective observational study in eight emergency departments. Patients taking >=1 regular medication, referred to the emergency department with a GP letter and seen by a pharmacist were included. GP medication regimens were compared with BPMH documented by the emergency department pharmacist. Results: Of the GP letters (total 414), 361 (87%) had one or more discrepancies in the patients' regular medications and 62% had one or more regular medication discrepancies of moderate-high significance. Omission of medication was more prevalent in handwritten letters (P