As a society develops and a standard of living raises, the orthoganthic operation, the purpose of which is the harmony of oral and surrounding tissue, the improvement of the basal bony relations for stable tooth-support, and the improvement of facial appearance, generalized in our society. This is a clinical study on 135 patients who underwent orthognathic operation at the Dept. of Oral and Maxillofacial surgery, College of Dentistry, Kyung-Hee University during the last 5 years. The results were as follows. 1. The ratio of female to male was 1.4 : 1. 2. The age distribution of most patients was the period of 20 years through 24 years. 3. The major reasons for seeking orthagnathic surgery were ethetic complanints(94.8%), and additional reason was functional complaints such as masticatory disturbances, phonetic disturbances, and TMJ discomfort. 4. In order to consult about orthognathic surgery, the patients first visited to the Dept. of oral and maxillofacial surgery at the ratio of 24.0%. 5. The ratio of the patients who underwent the presurgical orthodontic treatment was 79.5%, and the treatment usually required the period from 7 months to 18 months. 6. The setback amount was less than 10mm at the ratio of 85.8%. 7. The orthognathic operations which were practiced were usually composed of ramus osteotomy such as sagittal split ramus osteotomy and vertical ramus osteotomy and additional surgery on mandible at the ratio of 86.7%, and SSRO was done at the ratio of 62.5%, and EVRO was done at the ratio of 37.5%.