Uvulopalatopharyngoplasty (UPPP) is reported successful in treatment of obstructive sleep apnea for approximately 50% of patients. Several modifications of the procedure have been described, including transpalatal advancement pharyngoplasty, which resects a portion of posterior hard palate and advances the soft palate anteriorly. Comparing effectiveness of different techniques based on sleep and respiratory data is confounded by multiple variables including clinical failure at nonsurgical sites and imprecise patient selection techniques. Since pharyngeal surgical procedures prevent collapse and obstruction by structurally modifying the upper airway, measuring structural changes in size and collapsibility provides a method to compare techniques. To evaluate whether transpalatal advancement pharyngoplasty is more effective in modifying upper airway characteristics than UPPP, upper airway cross-sectional size and collapsibility were measured after UPPP and transpalatal advancement pharyngoplasty. Six patients were evaluated using a quantitative endoscopic technique. After transpalatal advancement pharyngoplasty maximal retropalatal airway size increased 321% from 29.7 +/- 9.9 to 95.3 +/- 16 mm2 (P < 0.01), and retropalatal closing pressure decreased from 4.7 +/- 1.6 to -3.8 +/- 0.7 cm/H2O (P < 0.01) compared with UPPP. Respiratory disturbance index decreased from 74.5 +/- 13.5 to 29.2 +/- 9 events/hour postoperatively (P < 0.05). Results support the conclusion that transpalatal advancement pharyngoplasty increases retropalatal size and decreases retropalatal collapsibility compared with UPPP. Since these characteristics are postulated to contribute to increased stability during sleep, transpalatal advancement pharyngoplasty may potentially improve UPPP outcome in selected patients with small retropalatal airway areas after traditional surgery.