Introduction:After a 6.0 magnitude earthquake struck Hualien on February 6, 2018, over one hundred and fifty patients crammed into the emergency department of a nearby tertiary hospital within two hours. The mass casualty incident (MCI) call was activated, and over 300 related personnel responded to the call and engaged with the MCI management.Aim:This research aimed to analyze the practice of an MCI call and to form the strategies to improve its efficiency and effectiveness.Methods:The research was conducted in a tertiary hospital in Hualien, Taiwan. Questionnaires regarding the practice of the MCI call were sent out to the healthcare providers in the emergency department who responded to that MCI operation.Results:Thirty-seven responders in the emergency department were involved in this study. 78% had participated in training courses for hospital incident command system (HICS) or MCI management before this event. On arrival at the emergency department, 69.4% of the responders were aware of the check-in station and received a clear task assignment and briefing. During the operation, 25.7% reported the lack of confidence carrying out the assigned tasks and 54.1% of the participants experienced great stress (stress score over 7 out of 10).Discussion:MCI is an uncommon event for hospital management. It is universally challenging owing to its unpredictable and time-sensitive nature. Furthermore, the administration could be further complicated by the associated disasters. Despite regular exercises and drills, there are still a significant number of participants experiencing stress and confusion during the operation. The chaotic situation may further compromise the performance of the participants. This study showed that optimizing task briefing and on-site directions may improve the performance of the MCI participants.