32 patients (15 male, 17 female) with a Class II were treated with the Reinach Modified Activator (RMA), a functional appliance characterized by an elongated anterior positioning plane and no attempted bite opening. The RMA was worn with or without additional headgear. No control group was incorporated in the present investigation as the appliance is still in an experimental stage. Patients were included whether co-operation was good or poor. The mean age at the beginning of treatment was 11.3 years and the average treatment time was 12.3 months. All patients had a mean ANB angle of 5.5° and an average Wits appraisal of 4.7 mm. Changes in cephalometric values were tested for significance by means of the paired t-test and the signed rank test. Decreases in the SNA (-0.8°), the ANB (-1.4°) and the Wits (-2.4 mm), as well as an increase in the SNB (+0.7°) were statistically highly significant. The upper incisors uprighted significantly (-2.9°) as did the lower incisors, but not significantly so. However, the mean ?-APog measurement increased significantly (+ 1.0 mm). This was especially noted in children > 11 years. No significant mean difference in the mandibular plane angle was found, but the facial axis did open significantly (+ 0.5°). In contrast, the facial contour angle remained unchanged. It was also observed that subjects treated longer than 6 months showed better improvement. Palabras clave: Functional appliance, Reinach Modified Activator (RMA), cephalometric changes