Background The electronic Survey of Anxiety and Information for Dentists (eSAID) allows children to tell dentists about their feelings and coping preferences. It is a computer “quiz” with 26 questions and free‐text responses that produces a report for the children that they can then hand to their dentist. This is the first study to report the use of eSAID in a hospital paediatric dental clinic. Methods This was a randomized controlled trial to evaluate whether children thought that eSAID benefitted them, made them less anxious, and improved cooperation and their treatment satisfaction. Fifty‐one children aged 8–13 years were randomized to complete either eSAID or a control version in the waiting room before their scheduled dental appointment. The study group had a 26‐item questionnaire; the control had only two items. Both groups scored their anxiety on a 7‐point anxiety scale at the start and again at the end of the quiz. All subjects handed the resultant eSAID report as a printout to their dentist. Dental treatment proceeded as planned. After treatment, each child reported how they thought the eSAID quiz had benefitted them by scoring on a 10 cm Visual Analogue Scale and their satisfaction on the Modified Treatment Evaluation Inventory. The operating dentists scored the children's cooperation using a 10 cm Visual Analogue Scale. Results Overall, the baseline anxiety levels were low (study: mean 1.2; control: mean 1.5). The study group's post‐survey anxiety reduced by 0.4, whereas controls' increased by 0.2; this difference is statistically significant (p = .04). However, it made no difference to the children's self‐reported benefit (p = .30), satisfaction (p > .05), or cooperation (p = .34). Conclusions eSAID reduced pre‐treatment anxiety but made no difference to children's perceived benefit, satisfaction, or cooperation. Future study should include known anxious children.