Objective: To examine the inter-rater reliability of triages performed by the Electronic Triage System (ETS) which has recently developed and used in hospital emergency department (ED).Methods: This cross-sectional study was conducted prospectively and studied 408 visitors of Tabriz Imam Reza hospital’s ED. The variables of interest were age, sex, nurse-assigned triage category, physician-assigned triage category, disease type (trauma, non-trauma), and the referred room within the ED. Cohen’s un-weighted kappa, linear weighted kappa, and quadratic weighted kappa were used to describe the reliability.Results: Un-weighted kappa observed to be 0.186 (95% CI: 0.123-0.249). Linear weighted kappa observed as 0.317 (95% CI: 0.251-0.384) and quadratic weighted kappa as 0.462 (95% CI: 0.336-0.589). In general, low agreement was seen between the triage nurses and ED physicians. For trauma patients and for those who were referred to the cardiopulmonary resuscitation room (CPR), all three types of kappa were higher than other visitors of the ED.Conclusion: Inter-rater reliability of the triages performed by the ETS observed as ranging from poor to moderate. Implementing interventions that would create a common language between nurses and physicians about the triage of the ED visitors seems necessary. The more agreement on the triage of trauma and CPR patients might be due to their condition and the more attention to them.