The aims of this interview-based questionnaire study were to establish which factors influence willingness-to-pay (WTP) for orthognathic treatment and to compare WTP values, from both members of the general public and orthognathic patients, with the actual cost of treatment, the hypothesis being that the more highly valued the intervention, the higher the WTP value. Data were collected from 88 orthognathic patients and a convenience sample of 100 adults using the so-called 'payment card' method. Demographic data were recorded, as well as ability to pay, incisor relationship, occupation, and level of education. In addition, the resources used in orthognathic treatment were estimated for five patients who participated in the study. The results showed that there was a significant difference between the mean WTP values for the public and patient groups. Patients were prepared to pay [see symbol in tex]2750 more than members of the general public. In addition, a significant relationship was found between WTP and incisor relationship in the patient group, with Class II division 1 patients prepared to pay [see symbol in text]3130 more than those with Class III malocclusions. Ability to pay did not significantly affect WTP. The mean total costs estimated for orthognathic treatment were lower than the mean patient WTP value and similar to the mean WTP value for the public group. In terms of cost-benefit, it appears that orthognathic treatment provides 'good value for money'. This study also showed that both patients and the general public were prepared to place a monetary value on the correction of dentofacial deformity and that this form of economic evaluation is a useful tool in monitoring health care in the UK.