Introduction: We aimed to test the predictive ability and to compare the predictive ability of the USEM to SRS, SORT and ASA in a prospective sample. Patients and methods: A Prospective cohort of >65 year old patients undergoing urgent abdominal surgery in a Hospital. Models calibration and discrimination were evaluated using the receiver operating characteristics curves and the Hosmer-Lemeshow test. Results: A total of 500 patients with a median age of 78 years were included. The AUROC in the validation cohort was 0.824. The USEM overestimated mortality (Test Hosmer-Lemeshow p < 0.001), after recalibration the USEM provided an accurate prediction of postoperative mortality. Conclusions: After the recalibration, the USEM had good discriminant power to estimate the risk of mortality in elderly patients after urgent abdominal surgery.