In this case report, the treatment of an 10 years and 7 months old girl with skeletal Class III malocclusion charecterized with maxiller retrognathia using RME and face mask appliance and 1 year follow up. The screw turned 2 times a day until sutura opens and 1 times a day after opens and the use of the face mask was started after obtaining adequate expansion. The elastics with 1000 g force with 20°–30° to the occlusal plane were adjusted and the patient was told to use them for least 16–18 hours. Skeletal and dental Class III with anterior crossbite corrected and soft tissue anomalies were obtained from the successful changes afer treatment for 12 months. Although our patient is in pubertal period, and fixed orthodontic treatment is not applied after obtaining dental Class I occlusion in patient, the amount of relapse is very low and after 1-year follow-up, the occlusion has been seen to be stable.

Keywords: Maxiller retrognathia, RME, Face Mask, Skeletal Class III