Background: There is a lack of epidemiological data on emergency Medical service (EMS) missions for accidents in Iran. The present study aimed at obtaining representative data on the epidemiology of emergency Medical service missions for accidents in Tehran. Methods: Active EMS stations in Tehran were selected through stratified random sampling in different regions of the city during a twelve-month period from March 2012 to March 2013. Data was collected through a questionnaire on demographic information, which extracted from events recorded on dispatch electronic forms in EMS. Data was analyzed by Excel using descriptive statistics. Results: Based on the type of accidents, Road Traffic Accidents (RTA) and downfall in the North, stab wound in the East, burning in the West, and poisoning with CO in the East region of Tehran megacity had the highest rates compared to other areas. The most common of all were Road Traffic Accidents (RTA) (77.9%) stab wound (11.1%), falling down (4.6%), burns (2.1%), and Carbon Monoxide (CO) poisoning (1.5%). Most accidents occurred in males and 20- to 40-year-old age group (45.51%), and the western district had the first rank in Tehran. Conclusions: According to demographic and geographical rate of accidents, It is recommended to develop preparedness programs and response plan according to epidemiological information of accidents. This programs includes EMS staff trainings and community educations.