The purpose of this study was to find out and evaluate discrepancies between exact and prediction values in Class III surgical patients. 26 patients(male 12, female 14) who were diagnosed as skeletal Class III and experienced presurgical orthodontic treatment and orthognathic surgery at Y university dental hospital were selected for this study. Lateral cephalograms were analyzed at prediction(T1), immediately after surgery(T2), 1 years after surgery(T3), and specified the landmark as coordinates of X and Y axes. The samples were divided into 2 groups depending on the rotation point of maxilla(A point vs Incisal Edge). The statistical tools was SAS program and the statistical significance was tested. The results were as follows: 1. Changes of hard tissue points (T1-T2) in x coordinates of ANS, A and in y coordinates of Me, Gn, Pg, B, Ii were statistically significant. 2. Change of soft tissue points (T1-T2) in x and y coordinates of Pn, Sn, STA, Ls, Li were statistically signinficant. 3. Statistically significant changes in maxillary surgery rotated at A point were in x coordinates of Ls, Li and in y coordinates of Me, Gn, Pg, B, Ii, Gn'and in x,y coordinates of Pn, Sn, STA. 4. Statistically significant changes in maxillary surgery rotated at Incisal edge were in x coordinates of ANS, A, Pn, Sn and in y coordinates of Me, Gn, Pg, B, Ii, Is, Ls, Li, Gn'and in x,y coordinates of STA. 5. There were significant differences in Is, PNS, Pn compared between A point group and incisal edge rotation group. 6. The maxillary plane angle showed significant difference at T2 - T3(p < 0.05), and occlusal planes of maxilla and mandible did not show significant change after surgery. As followed above results, the changes between prediction and exact measurements were considered separately at all landmarks and relapse amount according to surgery were also considered to achieve more reasonable surgical results.