Anxiety disorders are the most common mental illnesses in the United States. Despite having a number of medication options readily available, benzodiazepines (BZs) and antidepressants have achieved remission rates of only 35% after 8 weeks of acute treatment. In the development of new anxiolytics, particularly those that affect the gamma-aminobutyric acid system, it is essential to assess the new compound's potential to cause discontinuation symptoms after stopping the medication as part of both short- and long-term treatment. This report describes the development of the 20-item Penn Physician Withdrawal Checklist (PWC), a smaller version of the original 35-item PWC, and examines its validity, internal consistency, test-retest and interrater reliability, and factor structure. The PWC scores, assessed at the peak of withdrawal severity, were selected from 143 of our patients for an orthogonal factor analysis. Our results suggest that the Penn Physician Withdrawal Checklist is a simple and accurate method to assess anxiolytic discontinuation symptoms.