Background: Positional obstructive sleep apnea hypopnea syndrome (P-OSAHS) is a distinct OSAHS type. Whether velopharyngeal surgery is efficacious for patients with P-OSAHS remains unclear. Aim/Objective: To investigate the efficacy and factors influencing velopharyngeal surgery for treatment of patients with P-OSAHS, defined as the apnea hypopnea index (AHI) in different body postures (supine AHI >= 2*nonsupine AHI). Materials and Methods: A total of 44 patients with P-OSAHS who underwent velopharyngeal surgery were retrospectively studied. The clinical data of these patients, including polysomnography (PSG), physical examination, and surgical information, were collected for analysis. All patients underwent a PSG about 6 months after surgery to determine the treatment outcomes. Results: The overall AHI of the 44 patients decreased from 40.2 +/- 18.7 events/h to 18.5 +/- 17.5 events/h after surgery (P < .001). There were 29 responders (65.9%) according to the classical definition of surgical success. The percentage of sleep time with oxygen saturation below 90% (CT90) was the only predictive parameter for surgical success (P = .014, odds ratio value = 0.894). There was no significant difference between the change in supine AHI (-55.9 +/- 35.2%) and the change in nonsupine AHI (-43.4 +/- 74.1%; P = .167), and these 2 parameters were significantly correlated (r = 0.616, P < .001). Among the 38 patients with residual OSAHS (residual AHI >= 5), 28 had persistent P-OSAHS, and the percentage was as high as 82.4%. Conclusions and Significance: Patients with P-OSAHS with a lower CT90 value are more likely to benefit from velopharyngeal surgery. Positional therapy could be indicated for most of the patients who are not cured by such surgery.