Background: Emergency nurses are exposed to traumatized patients as part of their job. Secondary exposure to trauma may lead to traumatic stress similar to those experienced by the primary victim. Emergency nurses develop secondary traumatic stress symptoms more than other nurses due to nature of emergency departments. The consequences of secondary traumatic stress can be noticed at personal, interpersonal, or organizational level. Objectives: This integrative review aimed to explore the literature on the factors attenuate or enhance occurrence of secondary traumatic stress among emergency nurses, to identify these factors, and to provide recommendations for research in the field. Method: An integrative literature review of quantitative and qualitative studies on secondary traumatic stress in emergency nurses were published in English language between 2000 and 2017 through the following data bases: Cumulative Index to Nursing and Allied Health Literature (CINAHL), ProQuest, Medline, PubMed, Google Scholar, SAGE Journals, Wiley on Line Library, Science Direct and EBSCOhost Sources. Results: The review identified that factors associated with secondary traumatic stress can be classified into personal and organizational factors. Findings on personal factors such as age, gender, and experience are controversial, whereas organizational factors such as trauma case load and perceived organizational support were found to predict traumatic stress more than the personal factors. Conclusions: Emergency nurses are at risk to develop traumatic stress and need to be aware to the contributing factors in order to maintain their well being. Further research is required to explore the factors enhance or attenuate occurrence of secondary traumatic stress.