Objectives Frailty in older people associates with poor outcomes. Screening by ED physicians would greatly facilitate detection of frail older patients but our previous attempt to introduce routine ED-physician screening with Short Emergency Geriatric Assessment (SEGA), a 13-item frailty tool that French geriatricians use to identify frail patients, failed due to its length and complexity. A national committee recently generated a new version of the fast and simple 5-item Triage Risk Screening Tool (TRST) in which a subjective item (‘nurse concern’) was replaced by an item assessing basic activities of daily living. The ability of ED physicians using this French-TRST to accurately detect frail patients who require comprehensive geriatric assessment was assessed. Design Prospective cross-sectional study on diagnostic accuracy relative to the gold standard, namely, geriatrician-administered SEGA. Setting Tertiary-care hospital, France. Subjects and measurements The participants were 498 ≥75-year-old patients who visited the ED in 2018–2019 and were administered French-TRSTs by first ED physicians and then geriatricians, followed by SEGA, all within 24 hours. Diagnostic accuracy variables were calculated. Geriatrician-TRST was used to identify TRST items that associated with ED physician misclassification of frail patients. Results Emergency-TRST was significantly less sensitive than Geriatrician-TRST (88% vs. 93%; p=0.04) and tended to have lower negative predictive value (66% vs. 77%; p=0.09). Emergency-TRSTs rated four French-TRST items less well than Geriatrician-TRSTs. Conclusions As a substitute for SEGA in the ED, the French-TRST performed quite well overall but the ED physicians detected frail patients less well than the geriatricians. Modifications of the French-TRST that may improve the diagnostic performance of ED physicians are discussed.