Estimate in a sample of U.S. fire investigators the: (1) prevalence of generalized anxiety disorder (GAD), depression, post-traumatic stress disorder (PTSD) risk and mental health services use; and (2) association between organizational stigma and mental health disorders. Cross-sectional study design used to administer between November 2023 and January 2024, a 35-item behavioral/mental health survey. Approximately 18.0% of fire investigators had GAD, 22.8% depression, and 18.2% PTSD risk. Organizational stigma about mental health disorders was reported by 53.3% of fire investigators. The most frequently used behavioral/mental health services were cognitive behavioral therapy (40.1%) and medication management (36.1%). Organizational stigma around reporting mental health disorders was significantly associated with PTSD risk (aOR = 5.25;[2.41-11.43]). Mental health disorders are present in the fire investigator workforce and organizational stigma is associated with limited report of PTSD risk.