Continuous positive airway pressure (CPAP) is effective for patients with SAS. CPAP therapy requires long-term usage to prevent recurrence of symptoms. It is, thus, important to examine the level of long-term CPAP use and the factors influencing compliance with CPAP therapy for SAS. Compliance with CPAP therapy was examined in 204 patients in whom such therapy was started between 2003 and 2009. The median follow-up duration was 19 months (IQR = 6.8-37.5). Although the subjective and objective curative effects were significant, 18 patients (8.9%) refused CPAP therapy. Survival analysis showed that the patients' adherence to CPAP after 5 years was 89.8%. Multivariate analysis, including gender, age, BMI, AHI, arousal index, minSpO₂, ESS, sleep stage, and LMI, indicated that the degree of improvement of AHI, percentage of deep sleep stage, and LMI were clinical variables independently associated with long-term adherence to CPAP. Furthermore, use of appropriate drugs for the patients with nasal congestion resulted in better satisfaction and adherence to CPAP therapy. We have shown that the rate of compliance and the subjective and objective curative effects of CPAP therapy were high, and detected the independent clinical factors associated with continued CPAP therapy.