The aim of this study was to investigate the effects of modified Teuscher and van Beek functional appliances on the skeletal and dento-alveolar pattern in high-angle Class II, Division 1 patients. The collective consisted of 32 patients with a high-angle Class II, Division 1 malocclusion. The modified Teuscher activator was applied to a group of twelve patients, and the van Beek activator to a group of ten patients. A control group of ten subjects was used for comparison purposes. The mean chronological ages of the groups were 12, 11.8 and 11.5 years, respectively. 64 cephalograms taken before and after the treatment were evaluated. Intra-group measurement relations were determined by the Wilcoxon test, and inter-group relations by analysis of variance and Duncan tests, using SPSS statistical software. The following results were observed for both treated groups without any change in growth direction: inhibition of maxillary growth, stimulation of mandibular growth, retrusion of upper incisors, distal tipping of upper molars, and reduction of overjet and overbite compared with the control group. The decrease in overbite in the van Beek group was due mainly to intrusion of the incisors, and in the modified Teuscher group to molar extrusion. Both activators were considered preferable in terms of vertical control of the facial height in high-angle cases with deep overbite. However, stimulation of mandibular growth in the modified Teuscher activator group was found to be more significant than in the van Beek activator group.