Objectives. Screening for post-traumatic stress disorder (PTSD) takes place in clinical and research settings where diagnostic interviews are not feasible, and typically relies on self-report instruments like the PTSD symptom scale (PSS). Concerns have been raised about the specificity of PTSD symptoms assessed by questionnaires. This study examined whether the PSS distinguishes between patients with PTSD and those with other anxiety disorders or healthy controls. Design. A between-participants design was employed. Methods. The participants were 65 individuals with PTSD, 40 individuals with other anxiety disorders and 40 healthy controls. They completed the PSS with respect to a range of stressful life-events. Results. Using this instrument, 86% of individuals with PTSD and 5% of healthy controls endorsed sufficient symptoms to meet the PTSD diagnosis. This was also the case for 43% of individuals with other anxiety disorders, and self-reported symptoms related to traumatic events and aversive events that are generally not considered traumatic. Conclusions. The findings suggest that many people screened positive for PTSD may actually be suffering from another anxiety disorder.