Objective: The neutrophil -to- lymphocyte ratio (NLR) is a new predictor for cardiovascular risk and mortality. The SYNTAX score is an angiographic tool used in grading the complexity of coronary artery disease (CAD). However, its relation with CAD severity and complexity is not yet known. We hypothesized that NLR would be associated with a greater complexity of CAD as assessed using the SYNTAX score. Methods: This cross-sectional observational study included 106 patients who had undergone coronary angiography for stable angina pectoris and 69 patients who had normal coronary angiogram. Baseline NLR was measured by dividing neutrophil count to lymphocyte count. The patients were classified two groups as CAD (-)(n=69) and CAD (+)(n=106), then patients in CAD (+) group were divided into 3 groups according to SYNTAX scores (SYNTAX score 1-22, 23-32, >32) as pointed in European Society of Cardiology (ESC) revascularization guideline. Statistical analysis was performed using the Mann-Whitney U and Kruskal-Wallis tests, and multiple logistic regression analysis was used to identify the independent predictors of complexity of CAD-SYNTAX score. Results: Patients with CAD had a significantly higher value of NLR [1.6 median (1.2-3.3 IQR) vs. 2.3 median (1.8-3.0 IQR) p<0.001]. The group with high SYNTAX scores (>32) more frequently had diabetes mellitus (DM), hypercholesterolemia (HL), were of older age, and also had significantly elevated NLR values [2.4 (1.3-2.6), 2.6 (2.3-3.9), 2.0 (1.5-2.6) p=0.006]. In univariate analysis, age, DM, HL, creatinine, neutrophil count and NLR were predictors of high SYNTAX score. In the multiple logistic regression analysis, only NLR [odds ratio (OR)=2.1, 95% confidence interval (CI) 1.2-3.8, p=0.09], was identified as independent predictor of a high SYNTAX score. Conclusion: NLR is a strong clinical laboratory value that is associated with presence and complexity of CAD.