| Abstract BACKGROUND: Emergency Severity Index Version 4 (ESI v.4) is a validated triage tool for emergency departments, with an easy training system optimizing the allocation of limited resources to emergency patients. The present study aimed to determine the outcomes of triage with ESI v.4 method in all five levels of patients triage in emergency departments. METHODS: In this retrospective observational-descriptive study, following the training courses and implementation of triage with ESI v.4 method, the third quarter of 2008 was randomly selected for study. In this period, all patient files with their codes ending in zero were selected equaling one-tenth of all files. Triage levels and outcomes were extracted and the obtained data from 1309 were expressed using descriptive statistics. RESULTS: The mean age of the patients was 40.73 ± 21.37 years and 59.4% of the subjects were males. Classification of patients by ESI v.4 level was as the following: 1 (4.0%), 2 (11.6%), 3 (52.8%), 4 (25.5%) and 5 (6.1%). Hospitalization rate by ESI v.4 level was as below: 1 (80.76%), 2 (23.68%), 3 (25.75%), 4 (11.76%) and 5 (14.5%). CONCLUSIONS: The rate of hospitalization decreased from ESI level 1 to ESI level 5. Although the findings of this study were in line with the previous reports, some discrepancies indicated the existing inaccuracy in out-patient hospitalization system in the evening and night shifts and also at stage 5 triage level |