Changes in incisor inclination and position in both jaws of children during the first 5 years after adenoidectomy were studied. The main change is a significant increased labial inclination of the incisors for the adenoidectomy groups. All variables that measure the labiolingual position of the mandibular incisors confirm a significant labial incisor positioning for both sexes. Stepwise regression analysis shows that 41% to 44% of the incisor proclination after adenoidectomy is accounted for by two regressors--sex (female) and increase in the sagittal size of the nasopharynx. The study supports the hypothesis that a changed mode of breathing after adenoidectomy is associated with significant labial positioning of the incisor teeth.