Measurements of patients' perceptions of the benefits, costs and risks of orthognathic treatment are needed to assess the utility of alternative treatments, and to assess and improve patient education to make informed decisions. A two-part study was conducted to develop and evaluate measures assessing patients' perceptions of the benefits and risks of orthognathic surgery in coparison to an orthodontics-only approach or no treatment. The first part of this study included 49 patients who had completed orthodontics and orthognathic surgery and 34 patients considering orthognathic surgery. All patients were asked to complete an open-ended telephone questionnaire about their perceptions of the benefits and risks of orthognathic surgery and of alternative options. Patients' answers were sorted into categories, and the second part of this study included a closed-form written questionnaire to assess the perceived likelihood of possible outcomes in each category. Reliability of the questionnaire was assessed using Cronbach's alpha coefficient of internal consistency reliability. Cronbach's alpha ranged from 0.74 to 0.91 when the instrument was used to assess either overall benefits or risks of orthognathic surgery, orthodontics only, or no treatment, indicating acceptable reli ability for each of these uses. Subscales concerning more narrowly defined aspects of benefits and risks were less reliable than the overall scales.