© 2019 British Journal of General Practice. Background: Medication errors frequently occur as patients transition between hospital and the community, and may result in patient harm. Novel methods are required to address this issue. Aim: To assess the feasibility of introducing an electronic patient-held active record of medication status device (PHARMS) at the primary-secondary care interface at the time of hospital discharge. Design and setting: A mixed-methods study (non-randomised controlled intervention, and a process evaluation of qualitative interviews and non-participant observation) among patients >60 years in an urban hospital and general practices in Cork, Ireland. Method: The number and clinical significance of errors were compared between discharge prescriptions of the intervention (issued with a PHARMS device) and control (usual care, handwritten discharge prescription) groups. Semi-structured interviews were conducted with patients, junior doctors, GPs, and IT professionals, in addition to direct observation of the implementation process. Results: In all, 102 patients were included in the final analysis (intervention n = 41, control n = 61). Total error number was lower in the intervention group (median 1, interquartile range [IQR] 0-3) than in the control group (median 8, IQR (4-13.5, P<0.001), with the clinical significance score in the intervention group also being lower than the control group (median 2, IQR 0-4 versus median 11, IQR 5-20, P<0.001). The PHARMS device was found to be technically implementable using existing information technology infrastructure, and acceptable to all key stakeholders. Conclusion: The results suggest that using PHARMS devices within existing systems in general practice and hospitals is feasible and acceptable to both patients and doctors, and may reduce medication error.