Abstract: The Posttraumatic Stress Disorder (PTSD) Checklist for DSM-5 (PCL-5) is a widely used self-report measure of PTSD symptoms that has demonstrated strong psychometric properties across settings and samples. Co-occurring hazardous alcohol use and PTSD are prevalent among veterans, and the effects of alcohol use may impact the performance of the PCL-5. However, this possibility is untested. In this study, we evaluated the PCL-5 diagnostic accuracy for veterans who did and did not screen positive for hazardous alcohol use according to the Alcohol Use Disorders Identification Test-Consumption (AUDIT-C). Participants were 385 veterans recruited from Veterans Affairs primary care clinics. Results indicated that PCL-5 performance, AUC = .904, 95% CI [.870, .937], did not differ as a product of hazardous alcohol use. PCL-5 diagnostic utility was comparably high for veterans with, AUC = .904; 95% CI [.846, .962], and without, AUC = .904 95% CI [.861, .946], positive AUDIT-C screens. Although optimally efficient cutoff scores for veterans who screened positive were higher (i.e., 34-36) than for those with negative screens (i.e., 30), neither were significantly different from the overall PCL-5 cutoff score (i.e., 32), suggesting that neither veterans with nor without positive AUDIT-C screens require differential PCL-5 cutoff scores. The results do underscore the importance of using PCL-5 cutoff scores in concert with clinical judgment when establishing a provisional PTSD diagnosis and highlight the need for additional study of the impact of comorbidities on PCL-5 diagnostic accuracy and cutoff scores.