OBJECTIVE: To investigate the relationship of job stress and scores on the Minnesota Multiphasic Personality Inventory (MMPI) clinical scales in firefighters. METHOD: A total of 648 firefighters from Daegu Metropolitan City were given 2 sets of questionnaires, the Korean Occupational Stress Scales (KOSS) and the MMPI. The results of 428 qualifying questionnaires were analyzed using ANOVA, correlation, and multiple regression. RESULTS: The study demonstrated that job stress differed by age, department, amount of exercise, and duty period. MMPI clinical scales differed by age, smoking, and amount of exercise. Job stress correlated with MMPI clinical scales and in particular with 2 MMPI clinical scales, -Depression and Social introversion-. In addition, job stress subscales were related. On multiple regression analysis, some MMPI clinical scales were affected by job stress subscales. CONCLUSION: This study suggests that job stress is associated with psychogenic factors in firefighters. The effective management for job stress might be helpful for the overall mental health of firefighters. Further study is required to determine which psychogenic factors are related to job stress.