Abstract Objectives: Hypertrophic palatine tonsils play a role in the blockage of the upper airway, one of the known causes of Obstructive Sleep Apnea (OSA). Therefore, it is possible that there is an association between tonsil size and the success of pharyngeal surgery during OSA treatment. The main objective of this study was to evaluate the relationship between tonsil grade and volume, as well as to establish whether a relationship exists between tonsil size and the success rate of pharyngeal surgery (tonsillectomy and pharyngoplasty with barbed sutures). Methods: This retrospective study includes forty-four adult patients who underwent tonsillectomy and pharyngeal surgery with barbed sutures for the treatment of simple snoring and OSA between January 2016 and September 2019. Patients who had been previously tonsillectomized or those for whom tonsil volume measurement was lacking were excluded. All patients underwent a pre-operative physical exploration at the clinic exam room and a sleep study. Prior to surgery a Drug Induced Sleep Endoscopy (DISE) was performed. Tonsil volume was measured intraoperatively using the water displacement method. The same sleep study was repeated six months following surgery. Results: A significant correlation was found between tonsil grade and volume and between such measurements and the blockage observed at the level of the oropharynx during the DISE. Moreover, an association was observed between tonsil volume, but not tonsil grade, and the success of tonsillectomy and pharyngoplasty with barbed sutures. A tonsil volume greater than 6.5 cm3 was linked to success during pharyngeal surgery. Conclusion: A correlation exists between tonsil grade and tonsil volume. A bigger tonsil volume is associated with a greater success rate of oropharyngeal surgery during treatment of OSA. Level of evidence: Level 3, non-randomized cohort study.