Objective: This psychometric study explores the Portuguese version of the Posttraumatic Stress Disorder (PTSD) Checklist (PCL-5). It aims to clarify the best-fitting latent structure among competing PTSD models (Diagnostic and Statistical Manual of Mental Disorders-fifth edition [DSM-5], Dysphoria, Dysphoric Arousal, Anhedonia, Externalizing Behavior, And Hybrid models) and its implications for PTSD measurement. Method: Psychometric analyses were conducted in a sample from the general population of firefighters (N = 446), except the temporal stability, which was tested in a subsample of 100 participants. Results: The models presented significant differences in a global fit. The Hybrid model presented the best-fitting structure, but the DSM-5 model showed more favorable reliability and convergent validity in Confirmatory Factor Analyses. The DSM-5 model also proved to be internally consistency, temporally stable, and presented convergent validity. Conclusion: The Portuguese version of PCL-5 is reliable and valid. The findings suggest the appropriateness of the DSM-5 model to assess PTSD symptomatology, encouraging its use in clinical, and research settings. K E Y W O R D S firefighters, Portuguese version, Posttraumatic Stress Disorder Checklist for DSM-5 (PCL-5), Portuguese version, psychometric properties, PTSD model comparison