Anxiety assessment by questionnaire provides information for the dentist and may also confer a psychological benefit on patients. This study tested the hypothesis that informing dentists about patients' dental anxiety prior to commencement of treatment reduces patients' state anxiety. A randomized controlled trial was conducted involving eight General Dental Practitioners in North Wales. Participants included patients attending their first session of dental treatment, and accumulating a score of 19 or above, or scoring 5 on any one question, of the Modified Dental Anxiety Scale (MDAS). Patients (n = 119) completed Spielberger's state anxiety inventory (STAI-S) pre- and post-treatment and were randomly allocated to intervention (dentist informed of MDAS score) and control (dentist not informed) groups. Intervention patients showed greater reduction in mean change STAI-S scores (F[1,119] = 8.74, P < 0.0001). Providing the dentist with information of the high level of a patient's dental anxiety prior to treatment, and involving the patient in this, reduced the patient's state anxiety.