The purpose of this study was to examine a hypothetical model designed to explain the influence of length of work experience, frequency of mobilization, traumatic events, and depression on post-traumatic stress (PTS) in Korean fire fighters. Methods: In this study 2,181 fire fighters were surveyed and data collection was conducted from September 7 to September 30, 2009 using an structured questionnaire. SPSS and AMOS programs were used for descriptive statistics, t-test, ANOVA, and path analysis. Results: Frequency of mobilization, traumatic events, and depression showed direct effects on PTS for fire fighters, while length of work experience showed an indirect effect on PTS for fire fighters. The variables of this modified model explained 47.9% of the variance in PTS. Conclusion: Through this study the hypothetical model adequately explained PTS in fire fighters. Fire fighter``s PTS can be decreased by managing long-term work experience, frequency of mobilization, traumatic events, and depression. Based on the outcomes of this study, it is necessary to develop a Critical Incident Stress Debriefing (CISD) program for PTS.