Treatment response and stability of the anterior open bite malocclusion were evaluated in 20 open bite patients (17 females, 3 males), who were treated with the Edgewise appliance. The overbite, the number of teeth in occlusion, the functional occlusal contacts of the incisors and the cephalometric characteristics were studied before treatment (T1), at the end of retention (T2), and at least 1 year out of retention (T3). The apical root resorption of the upper incisors was analysed before and after treatment. The mean age at the follow-up control was 17 years 10 months. In 15 patients at least two occlusal contacts of the incisors were possible at the end of the retention period as well as at the follow-up control. The number of teeth in occlusion mesial to the second molars, expressed in percentage of the maximum possible, increased from 40 to 70 per cent during treatment with a positive tendency from T2 to T3. Apical root resorption of the upper incisors exceeded 10 per cent of the original root length in 4 out of 19 measurable cases. One of these patients had a history of trauma and the three others displayed atypical root form. Cases with an increased facial convexity, in which the uprighting of the incisors was possible, seemed to have a favourable treatment prognosis.