Background: With the release of the fifth edition of the Diagnostic and Statistical Manual for Mental Disorders (DSM-5), the Posttraumatic Stress Disorder Checklist (PCL) has been updated to meet the revisions of the diagnostic criteria for Posttraumatic Stress Disorder (PTSD). However, the diagnostic utility and reliability of a Brazilian version of the new Posttraumatic Stress Disorder Checklist (PCL-5) have not been investigated yet. Objective: To investigate the internal consistency, test-retest reliability, and diagnostic utility of the complete version (21-item) and two abbreviated (8-item and 4-item) versions of the Brazilian PCL-5. Methods: A total of 85 individuals with a history of exposure to at least one traumatic event underwent a diagnostic interview using the Structured Clinical Interview for DSM-5 (SCID-5-CV) and completed the Brazilian version of the PCL-5. Moreover, participants were invited to complete the checklist for a second time 10-30 days after the first assessment. Results: Both the complete and abbreviated versions of the Brazilian PCL-5 showed good internal consistency (complete PCL-5, α = .96; 8-item, α = .93; 4-item, α = .85) and test-retest reliability (complete PCL-5, ICC .87 [95% CI, 0.65-0.95]; 8-item, ICC .84 [95% CI, 0.60-0.94]; 4-item, ICC .84 [95% CI, 0.58-0.94]). Diagnostic utility analyses using the Structured Clinical Interview for DSM-5 (SCID-5-CV) revealed that a cutoff point of 36 presented the higher overall efficiency for predicting a PTSD diagnosis Overall Efficiency (OE, .80) and corresponded to Youden's index J (.65). For the 8-item version, a cutoff point of 13 corresponded to Youden's index J (.61), while scores of 21 or more were associated with the highest OE (.78). For the 4-item PCL-5, scores > 7 presented the highest OE (.77) and corresponded to Youden's index J (.59). Conclusions: Overall, the findings provide relevant evidence regarding the high reliability and diagnostic utility of this Brazilian version of the PCL-5. Propiedades psicométricas y utilidad diagnóstica de una versión brasileña del PCL-5 (versiones completa y abreviadas) Antecedentes: con la publicación de la quinta edición del Manual de Diagnóstico y Estadístico para los Trastornos Mentales (DSM-5), el Cuestionario para el Trastorno de Estrés Postraumático (PCL) se ha actualizado para cumplir con las revisiones de los criterios de diagnósticos del trastorno de estrés postraumático (TEPT). Sin embargo, la utilidad diagnóstica y la confiabilidad de una versión brasileña del nuevo cuestionario de trastorno de estrés postraumático (PCL-5) aún no se ha investigado. Objetivo: investigar la consistencia interna, la confiabilidad test-retest y la utilidad diagnóstica de la versión completa (21 ítems) y dos versiones abreviadas (8 y 4 ítems) del PCL-5 brasileño. Métodos: Un total de 85 individuos con antecedentes de exposición, al menos, a un evento traumático se sometieron a una entrevista diagnóstica utilizando la entrevista clínica estructurada para el DSM-5 (SCID-5-CV) y completaron la versión br...