Title: BOS Orthognathic DVD: RCT assessing patients’ knowledge and satisfaction Objectives: To compare patients’ knowledge of orthognathic treatment and satisfaction with their multi-disciplinary clinic consultation, after receiving information in a standard format versus standard format plus BOS Orthognathic DVD. Design: Multi-centred, randomised controlled trial. Setting: Multi-disciplinary orthognathic clinics at four hospitals in Merseyside, UK. Participants and Methods: 106 participants, age > 16 years, attending their first multi-disciplinary orthognathic clinic, were given information on orthognathic treatment in either the standard format – verbal and written or the standard format plus the BOS Orthognathic DVD. Primary outcome measures were participants’ knowledge of orthognathic treatment and satisfaction with their multi-disciplinary clinic consultation and information provided. Validated knowledge questionnaires were given prior to the multi-disciplinary clinic consultation and 4-6 weeks later. Satisfaction was assessed from participants’ response to 16 questions using visual analogue scale. Results of knowledge scores were analysed using ANCOVA at p < 0.05, and satisfaction using non-parametric Mann Whitney Wilcoxon test. Results: Knowledge scores improved from baseline in both groups. Baseline knowledge had a statistically significant effect on participants’ follow-up score. No significant difference in knowledge score was found between groups at follow-up once the baseline score had been accounted for. No difference in general satisfaction was found between groups. However, satisfaction with the DVD was significantly less than general satisfaction (p=0.015). Conclusions: There was no difference in participants’ knowledge of orthognathic treatment or satisfaction when given information in the standard format or standard format plus the BOS Orthognathic DVD.