Background:In most low- and middle-income countries (LMICs), the resources to accurately quantify injury severity using traditional injury scoring systems are limited. Novel injury scoring systems appear to have adequate discrimination for mortality in LMIC contexts,but they have not been rigorously compared where traditional injury scores can be accu-rately calculated. To determine whether novel injury scoring systems perform as well as traditional ones in a HIC with complete and comprehensive data collection.Methods:Data from an American level-I trauma registry collected 2008-2013 were used to compare three traditional injury scoring systems: Injury Severity Score (ISS); Revised Trauma Score (RTS); and Trauma Injury Severity Score (TRISS); and three novel injury scoring systems: Kampala Trauma Score (KTS); Mechanism, GCS, Age and Pressure (MGAP) score; and GCS, Age and Pressure (GAP) score. Logistic regression was used to assess the association between each scoring system and mortality. Standardized regression co-efficients(√β²),Akaike information criteria, area under the receiver operating charac-teristics curve, and the calibration line intercept and slope were used to evaluate the discrimination and calibration of each model.Results:Among 18,746 patients, all six scores were associated with hospital mortality. GAPhad the highest effect size, and KTS had the lowest median Akaike information criteria.Although TRISS discriminated best, the discrimination of KTS approached that of TRISS and outperformed GAP, MGAP, RTS, and ISS. MGAP was best calibrated, and KTS was better calibrated than RTS, GAP, ISS, or TRISS.