Pre- and post-treatment lateral radiographs of 120 former patients with skeletal class II, who had been treated with either an Andresen/Häupl type activator or bite jumping plates, were selected for this study. The evaluation results showed that bite jumping plates had a significant inhibition on the forward downward growth and the anterior rotation of the maxilla. The increase of the SNB-angle was significantly higher and there was also more posterior rotation of the maxilla in those patients, who had been treated with an activator. A two-way analysis of variance was carried out and it was possible to show that the independent treatment factors explained only 1/5 to 1/3 of the overall variance of the sample. The differences among the patients seem to depend more on individual growth patterns than just on the type of removable appliance.