This study was designed to analyse vertical dysplasia such as open bite or deep bite in persons with skeletal Class III malocclusion. The subjects consisted of 60 control patients, 40 Class III open bite patients and 40 Class III deep bite patients. The mean age was 19.8 years in the control group, 17.8 years in the Class III open bite group and 16.5 years in the Class III deep bite group. The results were as follows: 1. In Class III malocclusion patients, the characteristics of the vertical dysplasia are under the palatal plane. 2. In Class III malocclusion patients, the items showing the characteristics of the vertical dysplasia are mandibular plane angle, lower gonial angle, lower facial height, dental height & inclination of the upper first molar, interincisal angle, maxillary & mandibular occlusal plane angle. 3. In Class III malocclusion patients, LPFH/LAFH ratio shows the highest significance among the facial height ratios. 4. In Class III malocclusion patients, open bite group has a upward cant of maxillary occlusal plane & downward cant of mandibular occlusal plane. And deep bite group has a downward cant of maxillary occlusal plane & upward cant of mandibular occlusal plane. 5. In Class III malocclusion patients, the molar teeth of the open bite group are measially inclined and those of the deep bite group are upright.