The purpose of this study is to observe how the Class III intermaxillary elastics act upon the craniofacial structures of mixed dentition with anterior crossbites. The cephalometric head plates of 16 children treated only with Class III elastics (C III elastics group) and 23 children treated with Class III elastics and Reverse pull headgear simultaneously (C III elastics + RPHG group) were traced, digitized and statistically analyzed. The results were as follows. 1. Anterior displacement of maxilla was observed in both groups. 2. Simultaneous Class III elastics and reverse pull headgear group showed the counterclockwise rotation of maxilla, however Class III elastics group manifested no rotational change of maxilla. 3. Simultaneous Class III elastics and reverse pull headgear group showed the downward and backward rotation of mandible, however Class III elastics group manifested no rotational change of mandible. 4. Counterclockwise canting of occlusal plane, labial tipping of upper incisor and lingual tipping of lower incisor and mesial displacement of upper molar to pterygoid root vertical were observed in both groups.