This investigation was designed to compare the craniofacial morphology of Class III maloccusions with that of normal occlusions using PM line. The subjects consisted of forty-four normal occlusions (twenty-three amles and twenty-one females) and sixty-nine Class III malocclusions (thirty males and thirty- nine females), aged eight through ten. Using the tracings of the standard lateral cephalograms, various angles, linear measurements and linear ratios of counter-part were recorded and analyzed by t-test. The following characterstics of craniofacial morphology of Class III malocclusion were obtained by this study. 1. Maxillary anteroposterior position was balanced with Nasion but was not balanced with mandible because maxillary bony arch was small and positioned posteriorly and mandibular corpus was large and positioned relatively anteriorly. 2. Upper and lower alveolar bony arch were not balanced each other in its size. 3. In counterpart analysis, Class III malocclusion was more horizontally unbalanced than normal occlusion. 4. Class III malocclusion was divided into 11 groups by maxillary and mandibular bony arch position, size and alveolar bony arch size. Unbalanced bony size of the maxilla and mandible was a major characteristics of Class III mlaocclusion.