Background: Sleep apnoea hypopnoea syndrome (SAHS) is characterised by repetitive nocturnal hypoxemia and has a high prevalence among patients with acute myocardial infarction (AMI). But there are few studies on patients with AMI undergoing emergency primary percutaneous coronary intervention (pPCI).In this study, we want to find the prevalence of SAHS among patients with AMI undergoing emergency pPCI and determine whether SAHS would worsen the condition among these people, and especially affect the damage degree of the coronary artery Methods: Over four months, 95 patients admitted for the first time for AMI were observed. All of them had emergency primary PCIs. A total of 86 patients accepted the sleep study and were divided into four groups according to the apnoea hypopnoea index (AHI): SAHS was diagnosed when AHI ≥5/h and was defined as mild for AHI ≥5/h and <15/h, moderate for AHI ≥15/h and <30/h, and severe for AHI ≥30/h. On the contrary, the patients whose AHI <5/h were Non-SAHS. And the characteristics of the patients among these four groups were compared. According to the time of chest pain onset, the number of the patients between SAHS and non-SAHS, and patients' AHI during three intervals of one day were measured and compared;Makers including the sensitivity of serum troponin T (hs-TnT), creatine kinase isoenzyme MB (CK-MB), left ventricular ejection fraction (LVEF), pro-brain-type natriuretic peptide (pro-BNP), Gensini score and collateral vessels between the SAHS and non-SAHS were compared. And the relationships between the AHI of these patients and the markers were analysed. Results: Of the 86 patients studied, 65 had SAHS, representing a SAHS prevalence of 75.58% among patients with AMI undergoing emergency pPCI. There were significant differences in average ages, smoking and arrhythmia (P<0.05) between these four groups. There was no significant difference between AMI patients with or without SAHS regarding the day-night pattern. But there showed significant differences between SAHS and non-SAHS in Gensini score (P<0.05) and pro-BNP (P<0.05). Also, there were positive correlations between AHI and Gensini score (r=0.490, P<0.05) and pro-BNP (r=0.338, P<0.05). Conclusions: Among patients with AMI undergoing emergency pPCI, there is a high prevalence of SAHS.There are also positive correlations between AHI and Gensini score, and pro-BNP. Therefore, guided by the results, should we conduct a routine screening to those patients normally and could we relieve the damage to the coronary artery by curing the SAHS?