Background: Natural and man-made disasters affect people, communities, and health systems. Nurses play a key role in the health system and must be prepared for appropriate response in disasters. Objectives: This study was done to assess the current knowledge of nurses in emergency departments for disaster preparedness. Patients and Methods: This cross-sectional study was conducted on 110 emergency nurses working in teaching hospitals affiliated to the Iran University of Medical Sciences, Tehran, Iran. A questionnaire was used to collect data and the data were then analyzed using descriptive and inferential statistics with SPSS software version 16.0. Results: Based on the findings, most of the participants (64.5%) were aged 30 - 39 years old. 84% of the cases were female and 97.3% had a bachelor’s degree. The average perceived knowledge of nurses was 2.43 ± 1.01. The nurses had the highest familiarity with triage and lowest knowledge in epidemiology and decision-making. Conclusions: Lack knowledge of nurses regarding response to disaster situations indicates inefficiencies in the current system. Therefore, it is recommended to organize more workshops, annual training courses, and maneuvers based on staff needs and formulate continuous education courses for nurses.