Background and Objective: Evidence from past wars of human history and the present century presents undeniable examples revealing the importance of civil defense. In Iran, there have been numerous attacks with a variety of chemical gases during the eight years of the battle with Iraq. In addition, unintended accidents during earthquakes, hurricanes, and car accidents while transporting chemicals and chemical gases, although rare, are inevitable. For example, large-scale chlorine gas emissions have occurred. Because these events are rare, ED personnel are often not prepared enough to play an effective role in such situation, especially in the early golden hours after their happening. Due to lack of observation and repetition, preparedness of medical centers in terms of equipment and trained staff after the occurrence of attacks and accidents is a basic necessity. According to its inherent duties, Iranian civil defense organization is responsible for training and taking action to prepare hospital staff. This project, supported by this organization, aims to report how to confront with an accident or chemical attack in Loghman Hakim Hospital, a tertiary referral center for poisonings in Tehran, Iran, in 2019. Materials and Methods: This project was performed as a maneuver with participation of 65 physicians, hospital personnel, and students at Loghman Hakim Hospital affiliated to Shahid Beheshti University of Medical Sciences. Initially, training workshops were held to raise the awareness and preparedness of the members of the crisis team and all active staff using existing texts and instructions. Then, a designed imaginary scenario was presented and acted as a maneuver on a non-holiday day between 9. 30 AM and 4 PM. Results: Sixty-five physicians, hospital staff, and students attended the maneuver. The findings are reported in three levels of A: directorship and management level reaching almost 70% of its goals; B: operational level reaching about 70% of its goals, and C: termination of the maneuver and initiation of rehabilitation reaching almost 40% of its goals. Conclusion: The maneuver was performed with almost 65% of the aims reached. Physicians and staff readiness was assessed to be moderate. Lack of equipment was undeniably obvious, especially in decontamination tools and protective clothing for employees. In general, our referral center of poisoning is not prepared enough to deal with any chemical accident or attack if it happens. More attention is needed to chemical accident/attack preparedness at least in all referral centers for clinical poisoning throughout the country.