The American College of Surgeons (ACS) field triage guidelines are used to determine which patients require prompt transport to a trauma center and which can be transported to a lower-level facility. The objective of this report was to conduct a literature review to determine the sensitivity and specificity of the ACS field triage criteria and each step of the criteria. The bibliographic database MEDLINE was used to conduct a literature search for relevant English-language articles published between 1966 and 2005. The search was conducted by combining the Medical Subject Headings (MeSH) "emergency medical services," "triage," and "wounds and injury." To ensure that the search was comprehensive, the reference sections of all selected articles were searched for additional relevant references and searches by other organizations were reviewed to identify additional relevant articles. The MEDLINE search identified 542 titles. The author reviewed the titles, and 107 abstracts were selected for further review. Through the MEDLINE search, the reference section review, and the review of other searches, 80 articles were identified as relevant. Of those, five studies evaluated the full ACS criteria. Two of these calculated the specificity (8%) and/or sensitivity (95%-97%) of the ACS criteria. The remaining studies looked at the percentage of patients transported or admitted to a trauma center. Three studies looked at the predictive value of the physiologic step, and one of these calculated the sensitivity (56%) and specificity (86%). Two studies specifically analyzed the anatomic step. One of these calculated the sensitivity (45%). This search found that there is insufficient evidence to support the overall ACS field triage criteria. However, of the various steps, the physiologic and anatomic steps had the best evidence to support them.