Patients with malocclusion, especially those in need of surgical correction, have lower health related quality of life (HRQOL) and higher anxiety. We investigated the changes of HRQOL and psychological status following jaw surgery in the patients with facial deformities. Thirty-one adult orthodontic patients admitted to Tohoku University Hospital and diagnosed as malocclusion requiring jaw surgery were recruited for the study. The severity of malocclusion was assessed by Severity Score (SS) which is based on their cephalometric radiographs. They were divided into three groups according to the severity of malocclusion, i.e. Low-SS, Moderate-SS and High-SS. The subjects also completed a generic HRQOL (entire body health) instrument, and three disease-specific oral HRQOL instruments. HRQOL and psychological status of the patients were assessed before (T1) and at debonding of multibracketed appliances after surgery (T2). SS in each group significantly decreased to normal occlusion level (SS = 0-1). Oral function significantly improved from 11.8 ± 5.4 to 5.9 ± 4.3 in the Low-SS (p < 0.01), from 13.7 ± 6.5 to 8.8 ± 5.1 in the Moderate-SS (p < 0.05), and from 14.7 ± 6.7 to 7.8 ± 5.7 in the High-SS (p < 0.01). The patients after the surgical correction had improved disease-specific HRQOL and state anxiety irrespective of the severity before surgery, although the generic HRQOL, trait anxiety and depression were equal to that before the surgery. Furthermore, both postoperative anxiety and HRQOL were estimated by the preoperative anxiety and HRQOL. These results indicated that jaw surgery markedly improved the disease-specific HRQOL and psychological status in the present patients. We therefore suggest that assessments of the HRQOL and psychological status before treatment might predict the HRQOL and psychological status after the treatment to a certain extent.