Background Non ST-elevation acute myocardial infarction patients have a wide variation in their disease severity and clinical presentations.Therefore,Risk stratification is very important to obtain clinical decision.Several risk scores have been developed from different populations to estimate ischaemic risk.Among these several risk scores,the Global Registry of Acute Coronary Events (GRACE) risk score is the most widely used for risk stratification in NSTE-ACS;At present,many researches about GRACE risk score mainly focus on predicting short-or mid-term risk of ischaemic events and the degree of coronary stenosis.However,few study is about the relationship between GRACE score and severity of coronary artery disease (CAD) angiographically evaluated by Gensini score in patients with non ST-segment elevation myocardial infarction.So the aim of the present study was to evaluate the relationship between GRACE score and severity of coronary artery disease.