Background: Many organizations, especially at the time of accidents, disasters, and critical conditions, cannot provide their services without the presence of volunteers. When accidents and disasters occur, the first persons who normally appear at the scene are citizens. Volunteer citizens with the skills and local knowledge can play important roles when accidents and disasters occur and can provide valuable assistance to the relief forces. The current article aimed at examining the role of volunteer citizens in response to accidents and disasters.  
Materials and Methods: The current study examined the published articles from 2000 to 2016 based on the following keywords: informal volunteers in the disasters, challenges facing volunteer citizens in accidents and disasters, informal volunteers and disasters in local and foreign electronic databases including SID, Magiran, Iran Medex, ISC, Google Scholar, PubMed, ISI, and Scopus.
Results: Based on the search strategy, 50 articles were examined and the keywords, definitions, volunteer roles, role of volunteers in accidents and disasters, various types of informal voluntary activities, and volunteer citizens’ participation were examined. 
Conclusion: Studies referred to the roles, definitions, and challenges that informal volunteers face in various stages of accidents and disasters and the obvious point in the research was that more adaptive and comprehensive crisis and emergency management models are needed to utilize the capacities and flexibility of volunteers available within and between communities in disasters, and the network structure management can be helpful to manage the volunteers.