Background: Myocardial infarction in the absence of obstructive coronary artery disease (MINOCA) occurs in 5% to 10% of all patients with acute myocardial infarction. Obstructive sleep apnea-hypopnea syndrome (OSAHS) is linked to increased cardiovascular morbidity and mortality, but the relationship of OSAHS and outcomes in patients with MINOCA remains unknown. Objectives: We aimed to evaluate the association between OSAHS and clinical outcomes in patients with MINOCA.Methods and Results: Between January 2015 and December 2016, we carried out a prospective and consecutive cohort study of 583 patients with MINOCA and followed them up for three years. An apnea-hypopnea index of ≥15 events per hour recorded by polysomnography was defined as the diagnostic criterion for OSAHS. The primary end point was all-cause mortality, and the second end point was major adverse cardiovascular or cerebrovascular events (MACCE), a composite of cardiac death, nonfatal myocardial infarction, heart failure, cardiovascular-related rehospitalization, and stroke. All-cause mortality happened in 69 patients and MACCE occurred in 113 patients during the three-year follow-up. Kaplan–Meier survival curves indicated the significant relationship of OSAHS with all-cause mortality (log-rank P = 0.012) and MACCE (log-rank P = 0.002). Multivariate Cox regression analysis indicated OSAHS as an independent predictor of all-cause mortality and MACCE (adjusted hazard ratio: 1.714; 95% confidence interval (CI): 1.203–2.168; P = 0.013; and adjusted hazard ratio: 1.787; 95% CI: 1.249–2.236; P = 0.004; respectively), independent of age, sex, cardiovascular risk factors and discharge medications.Conclusions: OSAHS is independently associated with increased risk of all-cause mortality and MACCE in patients with MINOCA. Intervention and treatment should be considered to alleviate OSAHS-associated risk.