Abstract: AIM To investigate the correlation of global registry of acute coronary events (GRACE) score, neutrophil to lymphocyte ratio (NLR) and severity of coronary artery disease in patients with non-ST-segment elevation acute coronary syndrome (NSTE-ACS). METHODS Two hundred and twenty-eight NSTE-ACS patients with confirmed diagnosis by coronary angiography in our hospital were studied retrospectively. Another 44 patients with negative coronary angiography were selected as control group. According to GRACE risk score, NSTE-ACS group was divided into low risk group, moderate risk group and high risk group. Gensini score was utilized to definite the severity of coronary artery disease. Based on the tertiles of the Gensini score, NSTE-ACS group was divided into three groups: mild lesion group, moderate lesion group and severe lesion group. The association of GRACE risk score, NLR and different degrees of coronary artery disease was examined. RESULTS GRACE risk score, NLR and Gensini score in NSTE-ACS group were higher than those in control group (P<0.01). NLR and Gensini score of moderate group and high risk group were higher than those in low risk group (P<0.01). The incidence of three-vessel and left-main coronary artery disease in moderate group and high risk group were higher than that in low risk group (P<0.01). The GRACE risk score and NLR in severe lesion group were higher compared with those in mild lesion group (P<0.01). GRACE risk score and NLR score were positively correlated with Gensini score. GRACE risk score combined with NLR were of moderate value in predicting severe coronary artery disease (Area under ROC curve: 0.725,95%CI 0.653-0.798, P<0.01). CONCLUSION GRACE risk score and NLR have a good correlation with the degrees of coronary artery disease in non-ST-segment elevation acute coronary syndrome patients and they can be used as early predictors for serious coronary artery disease.