The assessment of dental anxiety can be achieved by using brief multi-item scales. Objective: To test the null hypothesis that completing the Modified Dental Anxiety Scale had no immediate influence on patient state anxiety. Outcome measure: Speilberger State Anxiety Inventory-6 item Short Form.Study design: Randomised controlled trial. Participants: Patients (n = 1,028) attending 18 dental practices in Northern Ireland were invited to participate. Results: Twenty-four patients refused (response rate 98%) providing 1,004 patients (mean age = 41 years, range = 16 to 90 years; 65% female) for analysis. Patients who completed the dental anxiety scale were found to have a virtually identical state anxiety score: mean (SD) = 11.36 (4.33) compared to those who completed the state anxiety assessment only: mean (SD) = 11.01 (4.35). The mean (CI95%) difference was 0.35 (0.89 to -0.18), t = 1.29, df1002, p = 0.2. Conclusion: The completion of a brief dental anxiety questionnaire before seeing the dentist has a non significant effect on state anxiety.