Abstract: AIM:To evaluate the relationship between serum cystatin C (CysC) level and the global registry of acute coronary events (GRACE) score in patients with non-ST segment elevation acute coronary syndrome (NSTE-ACS). METHODS: One hundred and fifty-five patients with NSTE-ACS were divided into non-ST segment elevation myocardial infarction (NSTEAMI) group and unstable angina pectoris (UAP) group and 87 patients without coronary heart disease (CHD) severed as control group. The GRACE score and CysC were measured and compared. RESULTS: In patients with NSTE-ACS, the level of serum CysC and the GRACE score significantly increased compared with those in control group. With the increase of GRACE risk score, the level of serum CysC significantly increased (P<0.05). The correlation analysis showed that GRACE scores had a positive correlation with serum CysC levels (r=0.549, P<0.01) and multivariate analysis demonstrated that age, creatinine and HDL were the main factors influencing the level of serum CysC. ROC curves analysis showed that the optimal cut-off point of CysC was 1.185 mg/L and the area under curve (AUC) was the highest (0.841), with a sensitivity of 69.7% and specificity of 89.3%. CONCLUSION: The level of CysC is closely related to CHD, which could be used as a better indicator of coronary atherosclerosis. Monitoring the dynamic changes helps to predict the occurrence and development of CHD. The higher the levels of CysC, the higher the GRACE scores in NSTE-ACS patients. Measurement of serum CysC level has an important clinical value for early risk stratification, prognosis and treatment options.