Introduction: Chronometry of patients' workflow in emergency department (ED) is influenced by and influencing on many factors. This study was designed to calculate the chronometric indices of patients' workflow in ED of 7th Tir Martyrs Hospital of Tehran, and to determine their associated factors. 

Methods: In this cross-sectional study, the population study are 649 records of patients attending in ED of 7th Tir Martyrs Hospital of Tehran, during 4-13 October 2008. Demographic data, route of entrance (EMS/Walk-in), traumatic/non-traumatic types, time durations, lab test and imaging request, other services visits, and work shift data were collected and analyzed by SPSS 12 through T-test

 Results: We found mean time between triage to visit 22 minutes, visit to disposition 210 minutes, disposition to exit 51 minutes, and triage to disposition 243 minutes. There were no statistically significant relationship between durations and sex, traumatic/non-traumatic patients and shift of work. There were statistically significant relationship between durations and route of entrance, lab test and imaging request, surgery and neurosurgery visits with triage to visit, visit to disposition and disposition to exit..

Conclusion: Mean triage to visit, visit to disposition, disposition to exit, and triage to disposition durations were closer to them, and these differences are related to route of entrance, lab tests and imaging request, surgery and neurosurgery visits..