Introduction: There has always been debate regarding the relationship between vertical growth pattern and obstruction of the upper and lower pharyngeal airways. Objectives:The present study was conducted to compare the dimensions of airway in cephalometric radiographs of patients with skeletal class I, II and III malocclusions, which all have a vertical growth pattern.Methods: 66 lateral cephalometric radiographs, all of which had a vertical growth pattern, were selected, and divided into three groups (class I, II and III). The points and reference lines required to measure the area of the airway were identifi ed. The percentage of the nasopharyngeal area occupied by the airway was calculated, and data were analyzed by SPSS version 25 software. The results were presented using ANOVA analysis of variance and multiple comparisons of Tukey HSD. The signifi cance level was 0.05 (P <0.05). Results:The mean percentage of nasopharyngeal space occupied by the airway was 44.72% in class I, 45.58% in class II, and 49.12% in class III, but their differences were not statistically signifi cant. Bony depth of nasopharyngeal space in class I is greater than in class II and class II greater than in class III, which had a signifi cant difference between class I and class III (P value= 0.027). Also, the bony height of the nasopharyngeal space in class III was greater than in class I and class I greater than in class II, which was signifi cantly different between classes II and III (P value= 0.017). Conclusion:Anterior-posterior malocclusion does not affect the nasopharyngeal bone area, the adenoid area, and the airway area, as well as the percentage of the air area.