BACKGROUND: frailty screening facilitates the stratification of older adults at most risk of adverse events for urgent assessment and subsequent intervention. We assessed the validity of the Identification of Seniors at Risk (ISAR), Clinical Frailty Scale (CFS), Programme on Research for Integrating Services for the Maintenance of Autonomy seven item questionnaire (PRISMA-7) and InterRAI-ED at predicting adverse outcomes at 30 days and 6 months amongst older adults presenting to the Emergency Department (ED). METHODS: a prospective cohort study of adults ¿65 years who presented to the ED was conducted. The ISAR, CFS, PRISMA-7 and InterRAI-ED were assessed. Blinded follow-up telephone interviews were completed at 30 days and 6 months to assess the incidence of mortality, ED re-attendance, hospital readmission, functional decline and nursing home admission. The sensitivity, specificity, negative predictive value and positive predictive value of the screening tools were calculated using 2¿×¿2 tables. RESULTS: a total of 419 patients were recruited; 47% female with a mean age of 76.9 (Standard deviation¿=¿7.2). The prevalence of frailty varied across the tools (CFS 57% versus InterRAI-ED 70%). At 30 days, the mortality rate was 5.1%, ED re-attendance 18.1%, hospital readmission 14%, functional decline 47.6% and nursing home admission 7.1%. All tools had a high sensitivity and positive predictive value for predicting adverse outcomes. CONCLUSION: older adults who screened positive for frailty were at significantly increased risk of experiencing an adverse outcome at 30 days with the ISAR being the most sensitive tool. We would recommend the implementation of the ISAR in the ED setting to support clinicians in identifying older adults most likely to benefit from specialised geriatric assessment and intervention.