Abstract. The main issue in determining seismic vulnerability is having a comprehensive view of all probable damages related to earthquake occurrence. Therefore, taking into account factors such as peak ground acceleration at the time of earthquake occurrence, the type of structures, population distribution among different age groups, level of education and the physical distance to hospitals (or medical care centers) and categorizing them into four indicators of geotechnical, structural, social and physical distance to needed facilities and from dangerous ones will provide us with a better and more exact outcome. To this end, this paper uses the analytic hierarchy process to study the importance of criteria or alternatives and uses the geographical information system to study the vulnerability of Tehran to an earthquake. This study focuses on the fact that Tehran is surrounded by three active and major faults: Mosha, North Tehran and Rey. In order to comprehensively determine the vulnerability, three scenarios are developed. In each scenario, seismic vulnerability of different areas in Tehran is analyzed and classified into four levels: high, medium, low and safe. The results show that, regarding seismic vulnerability, the faults of Mosha, North Tehran and Rey make, respectively, 6, 16 and 10% of Tehran highly vulnerable, while 34, 14 and 27% is safe.