Posttraumatic stress disorder (PTSD) diagnostic criteria have been criticized for including symptoms that overlap with commonly comorbid disorders, which critics argue undermines the validity of the diagnosis and inflates psychiatric comorbidity rates. In response, the upcoming 11th edition of the International Classification of Diseases (ICD-11) will offer PTSD diagnostic criteria that are intended to promote diagnostic accuracy. However, diagnostic utility analyses have not yet assessed whether these criteria minimize diagnostic errors. The present study examined the diagnostic utility of each PTSD symptom in the fifth edition of the Diagnostic and Statistical Manual for Mental Disorders (DSM-5) for males and females. Participants were 1,347 individuals enrolled in a longitudinal national registry of returning veterans receiving care at a Department of Veterans Affairs (VA) facility. Doctoral level clinicians assessed all participants using the PTSD module of the Structured Clinical Interview for DSM. Of the 20 symptoms examined, the majority performed in the fair to poor range on test quality indices. Although a few items did perform in the good (or better) range, only half were ICD-11 symptoms. None of the 20 symptoms demonstrated good quality of efficiency. Results demonstrated few sex differences across indices. There were no differences in the proportion of comorbid psychiatric disorders or functional impairment between DSM-5 and ICD-11 criteria. ICD-11 PTSD criteria demonstrate neither greater diagnostic specificity nor reduced rates of comorbidity relative to DSM-5 criteria and, as such, do not perform as intended. Modifications to existing symptoms or new symptoms may improve differential diagnosis.