This study was carried out to evaluate the distribution and the degree of the asymmetry existed in normal persons and asymmetric patients, and to investigate the changes of asymmetric patients after orthognathic surgery. The analysis was performed with the posteroanterior cephalometric radiography of 60 normal persons and 31 facial asymmetric patients. The results were as follows : 1. The degree of normal asymmetry existed in normal persons was not significant except MF and Me measurements. 2. The degree of normal asymmetry according to sex difference was not significant except cranial base area. 3. When normal persons were compared to asymmetric patients, there were more measurements which presented significant asymmetry on mandible than on maxilla. 4. When postoperative state was compared to preoperative state, the degree of asymmetry were usually decreased except AGO and GA measurements, especially the Cd, MF, Me, and Cd-Me measurements decreased significantly. 5. When postoperative state was compared to normal persons, 4 measurements of mandible approached significantly the measurements of normal persons.