A scale for assessing war-zone-related posttraumatic stress disorder (WZ-PTSD scale) was derived from the Symptom Checklist-90-R by identifying items that best discriminated Vietnam theater veterans with and without PTSD (N = 202). The 25-item WZ-PTSD scale had excellent internal consistency, and signal detection analyses revealed that its diagnostic utility was comparable to or exceeded that of several established PTSD scales and measures of global distress. In a cross-validation sample (N = 99), the diagnostic utility of the WZ-PTSD scale was stable, whereas other PTSD scales performed more poorly. The WZ-PTSD scale appears to be a valuable new measure of PTSD that can be particularly useful in archival data sets or in any situation where other PTSD measures are not available.