Background and objectives: The upper and lower airway has always been an area of interest because the oropharyngeal and nasopharyngeal structures play important roles in the growth and development of the craniofacial complex. Significant relationships between the pharyngeal structures and both dento-facial and craniofacial structures have been reported. The aim of the study were to evaluate Oropharyngeal and nasal passage volumes of patients with normal nasorespiratory functions having different dentofacial skeletal patterns using CBCT and the correlations between different variables and the airway Material and Methods: The study consisted of 45 patients (23 males, 22 females), divided into 3 equal groups as Class I , Class II and Class III based on evaluation of facial profile and molar relation. After obtaining CBCT, the Oropharyngeal airway volume (OPV), Nasopharyngeal airway volume (NPV), vertical height of oropharynx (HOP), Constricted minimum axial area (CMinAx), and Constricted posterior airway space (CPAS) were measured. Differences between groups were determined by using the Tukey Post Hoc test. Correlations between the variables were tested with the Pearson's correlation coefficient. Results: The mean OPV of the Class II subjects (6876.40 mm3) was significantly lower when compared with that of the Class I (8294.73 mm3 ) and Class III subjects (10941.43 mm3 ). The only statistically significant difference for NPV was observed between the Class I (9889.57 mm3) and Class II groups (7916.48 mm3 ). The CMinAx had a high potential in explaining the OPV. Conclusion: The results from this study indicate that mandibular growth deficiency patients had less airway volume, minimum axial area and constricted posterior airway space than the patients with good growth anteroposterior relationship between maxilla and mandible. The results of this research can be used as a guideline for subsequent works related to the airway study and presurgical assessment for orthognathic surgeries.