Objective: 1) To evaluate short- and long-term CPAP adherence in patients with hypertension and obstructive sleep apnea syndrome; 2) To investigate the predictors of short- and long-term CPAP adherence; 3) To explore the correlation between the CPAP adherence and blood pressure, target organ damage and the incidence of cardiovascular and cerebrovascular events. Study design: Prospective, multi-center, observational study. Study population: Patients with hypertension who are suspected to have obstructive sleep apnea syndrome due to snoring, daytime sleepiness and other related symptoms are considered eligible and should meet the following criterias: 1) Agree to participate in the study and sign the informed consent; 2) At least 18 years old; 3) STOP-Bang questionnaire, score ≥3 points; 4) Complete polysomnography in hospital; 5) Currently on CPAP therapy. Follow up: 3, 6 and 12 months after registry. Sample size estimation: At least 633 patients. Timeline: Start of subjects' enrollment: Jan 2023; End of subjects' enrollment: December 2026; End of study: December 2026. Organization: The Centre for Epidemiological Studies and Clinical Trials, Ruijin Hospital, Shanghai, China.