Background: HVA in mass gathering is usually named Hazard Vulnerability Assessment which is an important procedure in the effort to control health risks in mass gatherings. Mass gatherings, such as big sports championships or religious pilgrimages, present their own major issues to public health because they create high density of the population, requiring local health services capacity to rise and therefore risks of communicable diseases, injuries and other causes of emergency, Therefore, the research undertaken here is Assessment of the Hazard Vulnerability during Karbala religious mass gathering in Iraq\ on 20th Safar (Al Arbeen). Methodology: Descriptive study (retrospective) study between (2008-2012) covers: data collection of hazards assessment at health departments of ministry of health in Iraq. Results: Hazard Vulnerability assessment will be done as there had been occurrence of risks in the history of this events which occurred within the period between (2008-2012), which include: terrorist acts 1281 injured and 360 died, road traffic accident that mainly affected the male population and the poisoning accidents and other fires, the worst region with regard to injuries is Karbala (51.6%), whereas the high rate in death was 33.3%, and the road traffic accident in Karbala indicated a rise in those who As well the findings indicate that conversely, the poisoning accidents have the highest figures in 2010 and the fire accidents that have been occurring mainly in the shrine area being mainly as a result of electrocution. Discussion: The Challenges and risks for Al Arbaeen event indicates that displays of terrorist acts in Karbala 2008-2012 was greater and this impact on the medical services in Karbala specially in this event which has a big crowd. Conclusion and Recommendations: The medical plans used in this event should be modified and the incident command system all levels activated so as to reduce the hazards, this should be done in co-operation of the ministries and organizations (national and international) and Attabas (the shrines medical departments).