Problem statement:Considering the importance of emergency departments in healthcare system and the high mortality rate of patients referred to these departments, it is crucial to provide quality services in emergency departments. Accreditation is a systematic process for improving quality of care and it enables managers to assess and evaluate the healthcare system. Accreditation of an organization provides an obvious commitment for improving quality of safety, quality of patient care, ensuring safety surveillance and continuous activities for reducing dangers which threaten patients and staff. Therefore, given the vital role as well as and the perpetual and indispensable service provided by the emergency departments, it is necessary to re-evaluate the manner of service provision in these departments according to the standards and criteria of accreditation, so that an observance of these criteria will lead to improvement of emergency medicine in Iran. Thus, the present study was undertaken with the purpose of accreditation of emergency department of a teaching hospital of Tehran University of Medical Sciences according to the standards of Iranian Deputy of Health and the JCI. Approach: This is a descriptive-analytic study with a cross-sectional structure. Our study population consisted of 50 individuals of the healthcare staff (physicians and nurses) working in morning and evening work shifts of the emergency department in the teaching hospital. Data collection tools consisted of standard questionnaires of the Deputy of Health (9 series) and questionnaires developed by authors based on the standards of the Joint Commission International (JCI) regarding patient satisfaction with services provided in emergency departments. In order to determine the reliability and validity of the data collection tools, professors and experts reviewed the questionnaire of quality and patient safety in accordance with standards of quality patient safety from the standards of patient satisfaction prepared by the JCI. Subsequently, the questionnaires were used in the emergency department of a teaching Hospital with approval of the head of department. Moreover, they said questionnaire was critiqued for its content and then reviewed conceptually. The reliability of the questionnaire was confirmed with a Cronbach's α of 95%. Results: According to the relevant standards and the checklists provided by the Deputy of Health for influencing factors (such as human resources, ethical issues and observance of religious measures, structural issues, medical equipment and medications, provision of other medical services, nonmedical equipment), our evaluation of the emergency department in teaching Hospital yielded a score of 1626 points (86.81% of the maximum score) for the department. Conclusion: The above findings the emergency department in this hospital requires certain plans for improving the status quo. Therefore, the current deficiencies must be addressed with a comprehensive plan so that accreditation by the JCI may become feasible.