Background: Fatigue is one of the most debilitating symptoms in patients with respiratory disorders. In addition, mental disorders have a high frequency among chronic pulmonary disease. This study was applied to assess the relationship between fatigue and mental health in chemical victims with bronchiolitis obliterans. Materials and methods: In this descriptive cross-sectional study, 93 chemical warfare victims with bronchiolitis obliterans were selected and referred to respiratory clinic of Baghiatallah Hospital. Fatigue and mental health was measured with fatigue severity scale (FSS) and general health questionnaire (GHQ-12). Results: The majority of patients (80.6%) suffered from severe fatigue. Of the patients, 77.4% had no desirable mental health. There was a significant relationship between fatigue and mental health (P<0.0001). Conclusion: Fatigue and poor mental health status in the study population suggested the necessity of paying more attention to these two variables for health promotion and improve quality of life in chemical warfare victims.