Objective: To compare awake endoscopy with Müller’s maneuver (MM) during both sitting and supine positions, with drug-induced sleep endoscopy (DISE) as regard determination of different levels, patterns, and degrees of collapse of the upper airway in adult patients with obstructive sleep apnea (OSA). Methods: The study included adult patients with OSA symptoms, who had apnea hypopnea index (AHI) > 15. Patients were examined by MM in a sitting position, then during supine position; DISE then followed. Site, pattern, and degree of obstruction were assessed by experienced examiners according to the nose oropharynx hypopharynx and larynx classification. Results: Eighty-one adult subjects were included. The most common pattern of collapse at the retro-palatal level was the concentric pattern, while the predominant pattern at the hypopharyngeal level was the lateral wall collapse. The analysis of the pattern of collapse of the study group revealed that the individual pattern did not change (for the same patient at the same level) in the majority of patients whatever the maneuver or the position. Conclusion: This study demonstrates the feasibility of positional awake endoscopy for providing valuable surgical information as regard level, pattern, and degree of severity in OSA. The data of positional awake endoscopy were comparable to those gained from DISE with less morbidity and costs. The idea and results of this work provide a useful foundation for future research in this area. Multicenter studies are encouraged to obtain more reliable conclusions and more clear standards aiming at a better surgical planning.