The aim of this study was to compare the effects of the quad-helix/crib (Q-H/C) appliance and the open-bite bionator (OBB) in patients with open-bite malocclusions. The Q-H/C sample included 21 subjects, 15 girls and 6 boys. The average age for the Q-H/C group before treatment (T1) was 8.4 +/- 1.4 years, the mean age 1 year after active treatment (T2) was 10.9 +/- 1.6 years, and the mean duration of treatment was 2.6 years +/- 9 months. The OBB sample contained 20 subjects, 9 girls and 11 boys. The average ages were 8.3 years +/- 10 months at T1 and 10.8 +/- 1.5 years at T2. The mean duration of observation was 2.5 +/- 1.2 years. Lateral cephalograms were analyzed at T1 and T2. The T2 to T1 changes in the 2 groups were compared with a nonparametric test for independent samples (Mann-Whitney U test). The comparison between the 2 treatment protocols for skeletal open-bite malocclusion showed that the Q-H/C appliance is significantly more effective than the OBB for the improvement of overbite (+1.9 mm) in association with extrusion (+1.5 mm) and palatal inclination (+2.9 degrees) of the maxillary incisors.