The aim of this study was to evaluate the value of the Abbreviated National Early Warning Score (aNEWS) for predicting admissions and in-hospital mortality in elderly patients present to Emergency Department (ED). This retrospective, single-centred observational study was carried out in the ED of Minamitama Hospital, in Tokyo, Japan from 1 April 2018 to 30 April 2018. All of the patients aged 65 and older were included in this study. The aNEWS is based on six common physiological vital signs, including peripheral oxygen saturation, the presence of inhaled oxygen parameters, body temperature, systolic blood pressure, pulse rate, and the Alert, responds to Voice, responds to Pain, Unresponsive score. The scores range from 0 and 3 for each parameter. The aNEWS ranged from a score of 0 to a maximum of 17. The receiver operating characteristics (ROC) analysis was used to evaluate the predictive value of the aNEWS for admission and in-hospital mortality. The median aNEWS of patients admitted to the hospital was significantly higher than that of patients discharged from the ED (P<0.001). The median aNEWS of survivors was significantly higher than that of non-survivors (P<0.001). The Areas under the ROC Curve (AUC) for predicting admission was 0.773 [95% CI 0.7142 to 0.8317, P<0.001] for the aNEWS. The AUC for predicting in-hospital mortality was 0.791 [95% CI 0.604 to 0.978, P<0.001] for the aNEWS. Our single-centred study has demonstrated the utility of the aNEWS as a predictor of patient admission and in-hospital mortality in elderly patients.