A clinico-statistical observation was carried out on 808 patients, who underwent orthognathic surgery between 1982 and 2001 at First Department of Oral and Maxillofacial Surgery, Osaka Dental University Hospital.The results were as follows: 1. The number of patients with jaw deformity has increased in recent years. The total number of patients was 808 cases, about 60% of the total number of inpatients.2. The patients were 242 males and 566 females, and the ratio of males to females was about 1: 2.3.3. The age of patients who underwent surgery ranged from 14 to 48 years, with a mean of 21-25 years.4. Mandibular prognathism was the most predominant diagnosis (83%).5. Sagittal splitting ramus osteotomy (SSRO) was performed on most cases (86%).6. The average operation time and blood loss in SSRO were 2 hr and 38 min, and 158 ml, respectively. And those in Le Fort I osteotomy and SSRO were 4 hr and 27 min, and 405ml, respectively.