Background: Whenever there has been a worldwide contagious disease outbreak, there have been reports of infection and death of healthcare workers. Particularly because emergency nurses have contact with patients on the front line, they experience ethical problems in nursing while struggling with infectious diseases in an unfavorable environment. Objective: The objective of this study was to explore emergency nurses’ ethical problems and to identify factors influencing these problems during the outbreak of Middle East respiratory syndrome–coronavirus in Korea. Design and sample: (...) For this cross-sectional study, a questionnaire survey was conducted with emergency nurses working in six hospitals selected through convenience sampling from the hospitals designated for Middle East respiratory syndrome–coronavirus patients in the capital area. Methods: Data were collected from 169 emergency nurses in Korea during August 2015. Ethical considerations: This research was approved by the Institutional Review Board of G University in Korea. Results: The findings of this study suggest that during the Middle East respiratory syndrome–coronavirus outbreak, emergency nurses experienced ethical problems tied to a mind-set of avoiding patients. Three factors were found to influence emergency nurses’ ethical problems (in order of influence): cognition of social stigmatization, level of agreement with infection control measures, and perceived risk. Conclusion: Through this study, we obtained information on emergency nurses’ ethical problems during the Middle East respiratory syndrome–coronavirus outbreak and identified the factors that influence them. As found in this study, nurses’ ethical problems were influenced most by cognitions of social stigmatization. Accordingly, to support nurses confidently care for people during future health disasters, it is most urgent to promote appropriate public consciousness that encourages healthcare workers. (shrink)