BACKGROUND: Older injured persons are frequently undertriaged, increasing the risk for preventable mortality and morbidity in an already-vulnerable population. Changes made in 2006 to the American College of Surgeons Committee on Trauma (ACS-COT) Field Triage Decision Scheme might improve triage accuracy for this population. OBJECTIVE: This study examined triage accuracy before and after the 2006 revisions. METHODS: This secondary analysis of 2004, 2007, and 2008 data from the National Automotive Sampling System Crashworthiness Data System included persons aged 55 years and older who were transported to a hospital and had a maximum injury severity of uninjured or an Abbreviated Injury Scale score of 1 to 5. Trauma center and non-trauma center admission was a proxy for triage accuracy. Frequencies, means, standard deviations, sensitivities, specificities, positive predictive values (PPVs), and negative predictive values (NPVs) were calculated. RESULTS: Although triage accuracy has improved from 2004 to 2008, the undertriage rate still remains higher than the ACS-COT target of 5-10%. Overtriage rates have remained slightly above or within an acceptable range, suggesting that gains in triage accuracy have not unduly overburdened trauma centers. Both PPV and NPV have improved since 2004. CONCLUSIONS: There is a positive trend in triage accuracy for older injured persons since 2004. Ongoing funding, continued trauma system development with more training emphasis on scene evaluation of older adults, and the use of the ACS-COT triage decision scheme are essential for further improvement of triage accuracy. More research is needed to identify and validate additional triage criteria that are sensitive to severe injuries in older persons.