Background: The prognostic value of the Global Registry of Acute Coronary Events (GRACE) risk score (GRS) and the thrombolysis in myocardial infarction (TIMI) risk index (TRI) has been reported in coronary artery disease (CAD) patients. We aimed to evaluate the relationship between the GRS, TRI, and severity of CAD evaluated by SYNTAX score (SS) in patients Non ST segment elvation acute coronary syndrome (NSTE-ACS). Aim: The aim of this study is to compare the GRACE risk score and the TIMI risk index in predicting the extent and severity of coronary artery disease in patients with (NSTE-ACS) using Syntax score Methods: A total number of 100 patients were admitted to National Heart Institute CCU with NSTE-ACS undergoing coronary angiography. Patients with a history of coronary artery bypass surgery, those who had missing data for calculating the GRS and TRI, and those whose systolic blood pressure (SBP) was more than 180 mm Hg or whose diastolic blood pressure (DBP) was more than 110 mm Hg were excluded from the study The GRS and TRI were calculated on admission using specified variables. The severity of CAD was evaluated using the SS. The patients were divided into low (GRS 140) risk groups according to GRS score and into group 1 (TRI 0-2), group 2 (TRI 3-4), and group 3 (TRI 5-7) according to TRI score. A Pearson correlation analysis was used for the relation between GRS, TRI, and SS. Results: There were significant correlation between both GRACE and TRI score and SS (r=0.551, p<0.001) (r=0.309, p=0.046) respectively, there were no significant difference between area under the curve in predicting extent of CAD p= 0.185 although GRACE score showed higher significance in correlation with SS Conclusion: The GRS is more associated with SS than TRI in predicting the severity of CAD in patients with ACS