Background: Non-ST-segment elevation Acute Cronary Syndrome (NSTE-ACS) stays as the most common cause of mortality in people with cronary artery disease (CAD). Objective: The purpose of this research was to assess the probable association between the severity of CAD disease (by using the Syntax score) and c-reactive protein/albumin ratio (CAR) calculated by measuring serum levels upon admission. Patients and Methods: A prospective study that included 100 patients who were admitted to Agoza Hospital and Benha University Hospital with clinical features of NSTEMI and treated with percutaneous coronary intervention (PCI). We divided the patients into 2 groups: according to Syntax score, group 1 included 59 patients with Syntax score ≤ 22. Group 2 included 41 patients with Syntax score > 22.Results: Regarding laboratory findings in the studied patients, neutrophil was significantly higher in group 2 (7.6) than in group 1 (6) (P < 0.001). Platelets were significantly higher in group 2 (332%) than in group 1 (293) (P < 0.001). Median CRP was significantly higher in group 2 (14.8) than in group 1 (6) (P < 0.001). Median CAR was significantly higher in Group 2 (35.6) than in group 1 (14.6) (P < 0.001). Neutrophil to lymphocyte ratio (NLR) was significantly higher in group 2 (3) than in group 1 (2.5) P < 0.001). Left main cronary artery (LMCA) disease, three vessels disease (3VD), bifurcation, complete total occlusion (CTO), Lesion > 20 mm and severe tortuosity were significantly higher in group 2 than in group 1. Conclusion: GRS, LMCA disease, TVD, bifurcation, CTO, Lesion > 20 mm, severe tortuosity, neutrophil, platelets, median CRP, median CAR and NLR were significantly higher in those with Syntax score > 22 than those with syntax score ≤ 22. CAR was revealed to be an independent predictor for the high SS group, with a stronger correlation to the complexity and severity of CAD. Keywords: C - reactive protein - Serum albumin ratio - Severity of coronary artery disease - Non-ST elevated myocardial infarction.