Objective: To determine the effects of triage education based on emergency severity index (ESI) on promoting the knowledge and performance of nurses and qualitative indices of emergency department.Methods: This study was a quasi-interventional study being performed in Vali Asr Hospital of Fasa University of Medical Sciences during 2012. For this purpose, 50 members of staff including nurses and technicians of emergency medicine in the Emergency department with the inclusion criteria for participation were selected. Data collection instruments included a questionnaire consisting of two parts, (personal characteristics, and knowledge) and the performance assessment checklist was prepared. Content validity was used to determine the validity. The test-retest method and quder-Richardson 20 were applied to determine the reliability of the questionnaire. Interobserver reliability and the correlation between the two observers and imaging modalities were measured to determine the reliability of the performance checklist. The questionnaires and checklist were completed by the participants before, 2 days and 6 weeks after completion of the training. Workshop in two 9-hour sessions was provided which consisted of lectures, questions and answers.Results: The triage scores were 10.7±3.1, 17.8± 1.6 and 16.1±2.3 before, 2 days and 6 weeks after training, respectively. Triage performance score increased from 48.9 ± 9.9 before training to 59.8 ± 7.6, two days after training and to 59.7 ± 8.1 six weeks later (p=0.001). In addition to triage training of the nurses the emergency department qualitative indices were impressively upgraded. Other results showed that there was no significant correlation between individual characteristics and personal knowledge of triage score 6-week after training (r=0.018, p=0.126). However, significant positive correlation was found between nursing work experience, work experience in emergency ward and type of employment and performance scores 6 weeks after training (r=0.258, p=0.032).Conclusion: The results of the present study showed that triage education influences the practice and knowledge of nurses and improves the qualitative indices of emergency department. Therefore, it is recommended to include theoretical and practical training of triage for nurses in hospitals.