Purpose: This study aimed to evaluate the ANR(adenoidal nasopharyngeal ratio)on lateral cephalograms on assessing the upper airway volume using CBCT images as validation method.Methods: Thirty-two patients(mean age 11.8±1.6 years)were included in the study and it was essential that the lateral cephalogram and CBCT images taken at the examination were not more than 1 week apart.ANR was measured on the lateral cephalograms.The area and volumetric measurement of the nasopharynx(NP)and the total upper airway were obtained on CBCT images.Repeated measurements of ANR and airway volume were performed on 10 cases by two observers.