We conducted a retrospective study of 35 adults who had undergone tongue base suspension in addition to other surgery for the treatment of obstructive sleep apnea syndrome (OSAS). Our goal was to determine the most effective surgical approach by comparing these patients’ preoperative apnea-hypopnea index (AHI) with their postoperative scores at 6 months. The 35 patients were divided into three groups based on a preoperative assessment of their level of airway obstruction; the assessment included a determination of AHI and endoscopic findings during the Müller maneuver. Patients in group 1 (n = 9) exhibited unilevel obstruction, and they were treated with lateral pharyngoplasty; patients in group 2 (n = 13) also had unilevel obstruction, and they underwent Z-palatoplasty; patients in group 3 (n = 13) had multilevel obstruction, and they underwent combined surgery. Postoperatively, all three groups exhibited statistically significant improvements in AHI, but we determined that of the three approaches, multilevel surgery was significantly more effective (p < 0.001).