Objectives To evaluate the effect of maxillary protraction with facemask therapy on mandibular rotation taking into account the initial and final vertical growth pattern of each participant in order to evaluate our null hypothesis: The use of facemask in these patients does not modify their initial vertical growth pattern. Material and Methods A prospective single cohort study included children with Class III malocclusion treated with rapid palatal expansion and maxillary protraction with facemask. Cephalograms were taken before commencement and after completion of the facemask therapy with standardized equipment and magnification. Intraindividual cephalometric measurements were compared, and the vertical growth patterns were classified according to cephalometric standards. Potential changes in vertical growth pattern before and after completion of the facemask therapy was assessed by measuring Pearson's chi‐square and by multiple correspondence analysis. Results Thirty‐eight study participants were recruited, aged between 5.2 to 9.5 years (mean 7.5) at the commencement of facemask therapy, which lasted on average 1.6 years. Differences on pretherapy and posttherapy cephalograms were seen for linear rotational and sagittal measurements ( p < .01) as well as angular measurements of the cranial base, including an average palatal plane rotation of 0.45° (standard deviation: 1.78) and an average mandibular rotation of 0.39° (standard deviation: 2.19). The majority of participants maintained their initial vertical growth pattern after facemask therapy according to the multiple correspondence analysis ( p < .001). Conclusion Facemask therapy does not modify vertical growth pattern. The observed changes suggest a trend of maintaining each patient's initial growth direction after therapy.