Abstract: OBJECTIVE To study the prevention of upper gastrointestinal bleeding after acute coronary syndrome by pantoprazole and compound bismuth aluminate(CBA). METHODS A total of 167 in-patients with acute coronary syndrome from the year of 2006-2008 were enrolled in the study. The patients were divided into pantoprazole group(n=61), CBA group(n=55) and combined group(n=51). Besides，all the patients were treated with routine therapy. The morbidity of upper gastrointestinal bleeding after acute coronary syndrome was observed and recorded. RESULTS The morbidity of upper gastrointestinal bleeding after acute coronary syndrome was 13.11% in the pantoprazole group, 20.0% in the CBA group and 3.92% in the combined group, respectively. The difference among the three groups was significant(P<0.05). CONCLUSION Combination the proton pump inhibitor and CBA could prevent upper gastrointestinal bleeding after acute coronary syndrome.