The aim of this multi-centre retrospective study was to assess the cost, and factors influencing the cost, of combined orthodontic and surgical treatment for dentofacial deformity. The sample, from the south-west of England, comprised 352 subjects (109 males and 243 females) with an age range of 14 to 57 years treated in 11 hospital orthodontic units. Treatment costs were calculated for each subject by combining consumable costs with staff overhead and capital costs. The median total treatment cost was e6075.25 (interquartile range: e5139.41-e7069.68). Out-patient costs comprised 43 per cent. The median orthodontic treatment costs were e1456.23 (interquartile range: e1283.73-e1638.75). Orthodontic costs on average comprised 25 per cent of the total treatment cost. The cost of orthodontics for orthognathic patients in a hospital setting appears to represent excellent value for the state funded National Health Service in the United Kingdom.