Objectives: . Compliance with positive airway pressure (PAP) in patients with obstructive sleep apnea (OSA) directly affects its treatment efficacy. Since July 2018, polysomnography and PAP therapy have been covered by the National Health Insurance (NHI), which has reduced the price barrier and promoted PAP therapy in Korea. This study aimed to compare changes in PAP compliance before and after NHI implementation. Methods: . This study is a retrospective analysis in a tertiary hospital setting in Korea. From 2011 to 2019, patients with OSA (apnea-hypopnea index ≥5) treated using a PAP device for ≥1 month were included. They were classified as belonging to the pre-insurance (PI) group (having started PAP before July 2018) or the NHI group (having received a PAP reimbursement by the NHI service). We collected and analyzed medical records and PAP use information for between-group comparisons of compliance. We defined compliance as the percentage of usage days, the percentage of days with usage for ≥4 night hours, and average daily usage hours. Results: . We included 146 and 100 patients in the PI and NHI groups, respectively. Automatic PAP mode and NHI were independent predictors of compliance B at the 3- and 9-month follow-up points. The NHI group showed significantly higher compliance A at 3, but not 9 months. For compliance B, the NHI group showed significantly higher compliance than the PI group at 1 month and 3 months, but not at 9 months. Compared with the PI group, the NHI group showed significantly higher compliance C only at 3 months. Conclusion . The NHI has positively affected PAP therapy in patients with OSA. Insurance policy may affect compliance within the first 3 months of PAP therapy.