<p>This study aimed to determine whether ultrasonography can be used to assess the oropharyngeal airway in patients with obstructive sleep apnoea hypopnoea syndrome (OSAHS). 104 patients with OSAHS and 104 sex-, body mass index (BMI)-, and age-matched healthy subjects underwent oropharynx airway assessment using ultrasound. The dimensional changes of the oropharynx were monitored, and sonographic measurements of the airway lumen were obtained during deep breathing. Measurements were compared between groups. All suspected patients underwent Polysomnography in the sleep laboratory. OSAHS was defined as apnea-hypopnea index (AHI) &gt; 5 events/h. Adequate visualization of oropharyngeal dimensional changes was obtained in 95.19% of patients with OSAHS and 100% of healthy subjects. The anteroposterior diameter (AP) and lateral diameter (LAT) of the oropharyngeal airway of patients with OSAHS were smaller than those of healthy subjects at the end of deep inspiration and expiration (all <i>P</i> &lt; 0.05). Patients with OSAHS had greater lateral airway dimensional changes than the anterior-posterior dimension changes (<i>P</i> &lt; 0.001). The AP/LAT ratio of OSAHS at the end of deep inspiration was higher than that of healthy subjects (<i>P</i> = 0.012). Ultrasonography can detect the dimensional changes of the oropharyngeal airway in patients with OASHS during deep breathing. Patients with OASHS have a smaller airway size, a more circular configuration, and a more significant change of diameter in oropharynx airway than healthy subjects.</p>