Abstract Background Guidelines recommend that all older hospital patients are screened for cognitive comorbidity (i.e. dementia, delirium) and frailty to inform care and target multidisciplinary team resources based mainly on evidence from studies in outpatient or specialty-specific settings. Unselected hospital-wide data are needed to inform guidance and service design and delivery, so we set up the Oxford Cognitive Comorbidity and Ageing Research Database (ORCHARD) using routinely-acquired electronic patient record (EPR) data. Methods ORCHARD includes pseudonymised EPR data on all patients >65 years with unplanned admission to one of four general hospitals in Oxfordshire, serving a population of 660,000. Data collected include cognitive screening (mandatory for >70 years) comprising dementia history, delirium diagnosis (Confusion Assessment Method—CAM), and 10-point Abbreviated Mental Test; together with nursing risk assessments, frailty, diagnoses, comorbidities (Charlson index), observations, illness acuity, laboratory tests and brain imaging. Outcomes include length of stay, delayed transfers of care, discharge destination, readmissions, death and dementia through linkage to electronic mental health records. Results ORCHARD (2017-2019) includes data from 90,303 consecutive, unselected hospital admissions across all specialties (n=60,535 [67%] inpatient versus n=29,768 [33%] day case; n=73,385 [81%] medical versus n=16,918 [19%] surgical or other). Admissions data were linked to 46,533 unique individuals (n=23,724 [52%] female) with a mean/SD age of 78.3/9.6, Index of Multiple Deprivation Decile of 7.5/2.3 and Charlson Comorbidity of 8.1/9.4 at first admission. Frailty was prevalent, with 15,423 (33%) scoring moderate and 2,471 (5%) high on the Hospital Frailty Risk Score. Complete cognitive screening data are available for 34,416 (67%) unique individuals ≥70 years with inpatient admission. Conclusion ORCHARD is a large and rich data resource that will enable studies on the burden and impact of cognitive and physical frailty in-hospital, with relevance to the design and delivery of clinical services, and understanding of healthcare resource use hospital-wide and by specialty.