BACKGROUND Accurate triage of the undifferentiated patient is a critical task in prehospital emergency care. However, there is a paucity of literature synthesizing currently available prehospital triage tools. This scoping review aims to identify published tools used for prehospital triage globally and describe their performance characteristics. METHODS A comprehensive search was performed of primary literature in English-language journals from 2009 to 2019. Papers included focused on emergency medical services (EMS) triage of single patients. Two blinded reviewers and a third adjudicator performed independent title and abstract screening and subsequent full-text reviews. RESULTS Of 1521 unique articles, 55 (3.6%) were included in the final synthesis. The majority of prehospital triage tools focused on stroke (n = 19; 35%), trauma (19; 35%), and general undifferentiated patients (15; 27%). All studies were performed in high income countries, with the majority in North America (23, 42%) and Europe (22, 40%). 4 (7%) articles focused on the pediatric population. General triage tools aggregate prehospital vital signs, mental status assessments, history, exam, and anticipated resource need, to categorize patients by level of acuity. Studies assessed the tools' ability to accurately predict emergency department triage assignment, hospitalization and short-term mortality. Stroke triage tools promote rapid identification of patients with acute large vessel occlusion ischemic stroke to trigger timely transport to diagnostically- and therapeutically-capable hospitals. Studies evaluated tools' diagnostic performance, impact on tissue plasminogen activator administration rates, and correlation with in-hospital stroke scales. Trauma triage tools identify patients that require immediate transport to trauma centers with emergency surgery capability. Studies evaluated tools' prediction of trauma center need, under-triage and over-triage rates for major trauma, and survival to discharge. CONCLUSIONS The published literature on prehospital triage tools predominantly derive from high-income health systems and mostly focus on adult stroke and trauma populations. Most studies sought to further simplify existing triage tools without sacrificing triage accuracy, or assessed the predictive capability of the triage tool. There was no clear 'gold-standard' singular prehospital triage tool for acute undifferentiated patients. BACKGROUND Not applicable.