The Penn State Worry Questionnaire (PSWQ) is widely regarded as the gold standard self-report questionnaire for pathological worry. However, the factorial structure of the scale remains contentious. We sought to determine whether a psychometrically sound brief version of the PSWQ, which avoids contentious items and yet incorporates the essential features of pathological worry, could be derived from the existing PSWQ item pool. After inspecting items of the PSWQ and the findings of previous factor analytic studies, three items were selected that capture the essence of pathological worry (i.e., high frequency, perceived uncontrollability and multiple domains of worry), according to the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition). We then compared the psychometric properties of the 3-item PSWQ with the full PSWQ in a sample of 225 clients attending an anxiety disorders clinic. Despite its brevity, the 3-item PSWQ had internal consistency comparable with that of the standard PSWQ, and performed equally well with regards to convergent and discriminant validity, in screening for a generalized anxiety disorder diagnosis and in detecting change with treatment. The 3-item ultra-brief version of the PSWQ is quick to administer, simple to score and possesses psychometric properties very similar to the 16-item version. Further research should confirm the psychometric properties of the 3-item version when administered independently of the other items and assess the scale's test-retest reliability.