ABSTRACT: Importance:Suicide rates are higher among veterans compared with nonveterans, and the prevalence of posttraumatic stress disorder (PTSD) is higher among veterans compared with the general adult population in the US. To date, no study has examined the association between PTSD screening results and suicide mortality among veterans. Objective:To examine whether veterans receiving care in the US Veterans Health Administration (VHA) health system who had positive results on the Primary Care-Posttraumatic Stress Disorder Screen (PC-PTSD) had a greater risk of suicide mortality compared with those who had negative results and to assess whether such risk decreased over time. Design, Setting, and Participants:Multivariable proportional hazards regression models were used to evaluate suicide mortality risk through December 31, 2016, among a cohort of veterans who received the PC-PTSD in the VHA health system. The VHA administers the PC-PTSD to patients nationwide, and screening results are routinely documented in the VHA Corporate Data Warehouse. The PC-PTSD includes 4 questions regarding PTSD symptoms, to which patients respond with either a positive (yes) or negative (no) answer. All patients who completed the PC-PTSD in 2014 and who did not have a diagnosis of PTSD in the year before screening were included in the analysis. A score of 3 or 4 on the PC-PTSD indicated a positive result, and a score of 0, 1, or 2 indicated a negative result. Data collection and analyses were performed from November 13, 2018, to June 18, 2019. Exposures:Primary Care-Posttraumatic Stress Disorder Screen (PC-PTSD). Main Outcomes and Measures:Suicide mortality risk, as assessed through data obtained from the US Veterans Affairs/Department of Defense Mortality Data Repository. Results:A total of 1?693?449 PC-PTSDs were completed by 1?552?581 individual veteran patients in 2014. Most of the patients were White (73.9%), married (52.2%), male (91.1%), 55 years or older (62.5%), and had completed only 1 PC-PTSD (92.1%). In multivariable analyses, positive PC-PTSD results (ie, total scores of 3 or 4) were associated with a 58% increase in the risk of suicide mortality at 1 day after screening (hazard ratio?[HR], 1.58; 95% CI,?1.19-2.10) and a 26% increase in the risk of suicide mortality at 1 year after screening (HR,?1.26; 95% CI,?1.07-1.48). A positive response on item 4 ("felt numb or detached from others, activities, or your surroundings") of the PC-PTSD was associated with a 70% increase in suicide mortality risk at 1 day after screening (HR,?1.70; 95% CI,?1.27-2.28). Conclusions and Relevance:Positive PC-PTSD results, and specifically reports of feeling numb or detached, were associated with increases in the risk of suicide mortality. These associations decreased over time. The findings of this study can inform interpretation of PC-PTSD responses and suggest the importance of recent improvements made to the VHA suicide risk assessment.