We have been treating a girl with hemifacial hypertrophy since she was 5 years 8 months old. We analyzed her stomatognathic function, the dentition and occlusion, X-ray findings of TMJ, tooth contact and measurements of mandibular movement, at 9 years 2 months. The results were as follows: 1. The maxillary dental arch was almost symmetrical, but the mandibular one was complicatedly distorted in the up and down directions, and largely shifted to the left side. As a result the patient was able to occlude in the severe cross-bite condition of the area from incisors to left molars. 2. The patient had many tooth contact points on the right side and few on the left side when she bit at the intercuspal position and at the both lateral excursions. 3. From the analysis of the mandibular movements on the protrusion, lateral excursion and maximum open and close positions, it was suspected that the shift of right condyle was much less than the left one, and showed as almost rotating movement. 4. It could be concluded that the patient was accustomed to having more tooth contacts in the right dentition than in the left one because of the hypertrophy of the right half of mandible, so that she could only masticate with the right teeth also the anterior displacement of disk with reduction was resulted on the right condyle and the asymmetrical mandibular movement was noted.