Low adherence to secondary prevention medications (ATM) of patients after acute coronary syndrome (ACS) is associated with poor clinical outcomes.However,literature provides limited data on assessment of ATM and risks associated with poor in Chinese patients with ACS.In the current work,ATM was assessed in consecutively recruited patients with ACS in Tongji Hospital from November 5,2013 to December 31,2014.A total of 2126 patients were classified under low adherence (proportion of days covered (PDC) ＜ 50％) and high adherence (PDC＞50％) groups based on their performance after discharge.All patients were followed up at the 1st,6th,and 12th month of discharge while recording ATM and major adverse cardiac events (MACE).Bivariate logistic regression was used to identify the factors associated with ATM.Cox regression was used to analyze the association between ATM and MACE within one year after discharge.Results showed that coronary artery bypass grafting (CABG) alone had significantly lower proportion of high adherence to P2Y12 antagonists (83.0％ vs.90.7％,P ＜ 0.01) than patients treated with percutaneous coronary intervention (PCI) only.Moreover,in patients undergoing PCI,high adherence to P2Y12 antagonists decreased the risk of MACE (hazard ratio =0.172,95％ confidence interval:0.039-0.763;P=0.021).In conclusion,PCI-treated patients are more prone to remaining adherent to medications than CABG-treated patients.High adherence to P2Y12 antagonists was associated with lower risk of MACE.