BACKGROUND: Trauma systems decrease morbidity and mortality of injured populations, and each component contributes to the final outcome. This study evaluated the association between a referring hospital's trauma designation and the survival and resource utilization of patients transferred to a level I trauma center. METHODS: Data from the Registry of the American College of Surgeons on patients transferred to a level I trauma center during a 7-year period were subdivided into 3 categories: group 1 = level III-designated trauma center; group 2 = potential level III trauma centers; and group 3 = other transferring hospitals. Trauma and Injury Severity Score methodology was used to provide a probability estimate of survival adjusted for the effect related to injury severity, physiologic host factors, and age. A W statistic was calculated for each type of referring hospital so that comparisons between observed survival and predicted survival could be measured. Differences in W, length of stay, intensive care unit days, and ventilator days were examined using general linear models. RESULTS: Patients transferred to a level I from a level III trauma center (group 1) were more seriously injured (P < .0001) and had improved survival (P < .0018) compared with those transferred from nondesignated hospitals (groups 2 and 3). Patients transferred from large nondesignated hospitals (group 2) had outcomes similar to patients transferred from all other hospitals (group 3). Level I hospital resource utilization did not show significant differences based on referring hospital type. COMMENTS: Outcomes of patients in a trauma system are associated with trauma-center designation of the referring hospitals.