Background: Triage of trauma patients is particularly important. Correct triage can reduce the rate of mortality and prevent disability in trauma patients. Objectives: The current study aimed at comparing the frequency of miss triage using the two methods namely emergency severity index (ESI) and shock index, in patients with abdominal trauma. Methods: Trauma patients referring to Shahid Rajaee hospital, were included as the study population. A census survey was conducted for three months. Data were collected by a demographic questionnaire, a five-level triage system checklist, and triage form based on the shock index. Content validity of the questionnaire was confirmed by experts and Patients were simultaneously evaluated by both ESI and shock index methods. The triage level in each method was compared with the triage level approved by an emergency clinician. Data were analyzed with SPSS version 18. Results: Based on ESI, 6.3% of patients were under-triaged and 2.7% over-triaged; but based on the shock index, 36.2% of the patients were under-triaged and 19.2% over-triaged. There was a positive correlation between each of the two methods and the final score of triage. Moreover, the correlation coefficient of the final score in the five-level triage system was higher than that of the shock index (r = 0.834 vs. r = 0.162). Conclusions: According to the results, the shock index can be used as an auxiliary tool in the triage of traumatic patients in emergency departments.