Study Objectives To investigate whether uvulopalatopharyngoplasty (UPPP) improves sleep quality in patients with Obstructive Sleep Apnea (OSA) using the Functional Outcomes of Sleep Questionnaire (FOSQ) and the Karolinska Sleep Questionnaire (KSQ). Methods Randomized controlled trial used to compare modified UPPP, with controls at baseline and after six months. The controls received delayed surgery and a six-month postoperative follow-up. All operated patients were offered a 24-month follow-up. At each follow-up, patients underwent polysomnography and vigilance testing and completed questionnaires. Nine scales were evaluated: five subscales and the total score in the FOSQ and three subscales in the KSQ. Results Sixty-five patients, mean 42.3 years (SD 11.5), Friedman stage I and II, BMI <36 kg/m 2, moderate to severe OSA, were randomized to intervention (n = 32) or control (n = 33). In the FOSQ and in the KSQ, the mean rate of missing values was 6.2% (range 0-19%) and 20.5% (3-38%), respectively. In 8 of 9 scales, significant differences were observed between the groups in favor of UPPP. There were significant correlations between results from the questionnaires and objective measures from polysomnography and the vigilance test. At the six and 24-month postoperative follow-ups, 8 of 9 scales were significantly improved compared to baseline. Conclusions In selected patients with OSA, subjective sleep quality was significantly improved six months after UPPP compared to controls, with stable improvements 24 months postoperatively. The correlations between subjective and objective outcomes, and the long-term stability suggest a beneficial effect from surgery, although a placebo effect cannot be excluded.