METHODS: A total of 123 patients with ACS were classified into four groups according to results of coronary angiography (CAG) and polysomnography (PSG): ACS group (group Ⅰ, n=31), ACS complicated with mild OSAHS (group Ⅱ, n=31), ACS complicated with moderate OSAHS (group Ⅲ, n=31), ACS complicated with severe OSAHS (group Ⅳ, n=30). Patients’ information including age, sex, body mass index, history of hypertension, diabetes mellitus, family, smoke, total cholesterol (TC), triglyceride (TG), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), results of CAG and PSG were collected. Coronary artery lesions’ were compared by Gensini score. The relationship between Gensini score and apnea hypopnea index (AHI) and minimum SaO2 during sleep at night were analyzed. The patients were followed up for six months, and the amounts of cardiovascular composite endpoint in four groups were compared.