Inclusion Criteria:  BMI of patients less than 35 kg/m2. Patients who have symptoms and signs of OSA. Moderate to severe OSAHS confirmed by formal polysomnography (defined as an AHI ≥15). Friedman tongue position III or IV. Documented failure/refusal of attempts of conservative treatment measures (not limited to continuous positive airway pressure). The presence of retrolingual collapse confirmed preoperatively with flexible fiberoptic endoscope during Muller maneuver. Patients have macroglossia as defined by posterior airspace (PAS) of ≤10mm.  Exclusion Criteria:  Failure to attend postoperative follow-up polysomnography within 6 months of surgery. Previous surgery to the base of the tongue or other surgical treatment of OSAHS. A history of malignancy or infection of the head and neck region, laryngeal trauma, or other previous oropharyngeal/laryngeal surgery. Patients have retrognanthia sella-nasion-supra mentale (SNB) ≥76º. Huge lymphoid tissue of the tongue and/or lingual tonsil.