Objective: To validate the triage ratings performed by the Electronic Triage System (ETS) using hospitalization, length of stay, resource use, in-hospital mortality and patient bills as outcome measures.Methods: In this retrospective cross-sectional study the medical records of 387 patients were reviewed in a one-week period. The data included triage category and the outcome measures were hospitalization, length of stay, in-hospital mortality, patient bill, and used resources. The association between the triage category and hospitalization and death was assessed. The association between the triage category and the number of resources, length of stay, and the bill was also assessed.Results: The mean age of the patients was 43.65 ±21.17 years. Women comprised 40% (n=155) of 387 people who were included in the study. The frequency of Emergency Severity Index (ESI) 1, 2, 3, 4 and 5 categories were 18, 61, 127, 181 and 0 respectively. Phi and Cramer’s V for hospitalization and death were 0.365 (p<0.001) and 0.305 (p<0.001). Spearman's rho for bill, length of stay, and resource use were -0.483 (p<0.001), -0.228 (p<0.001) and -0.490 (p<0.001). The association between triage category and resource consumption was stronger than other outcomes.Conclusion: The ETS was valid in predicting all studied patient outcomes. The ETS has also the advantages of providing quick reports, giving feedback and providing data for research purposes.