Objective: Nesfatin-1 is a novel anorectic neuropeptide with potent metabolic regulatory effects. It regulates blood pressure, heart rate, cardiomyocyte metabolism and permeability. SYNTAX score, which is an angiographic scoring system, defines the grade and complexity of coronary artery disease (CAD).We aimed to evaluate the relationship between nesfatin-1 level and severity of CAD according to the SYNTAX score in patients with non-ST segment elevation myocardial infarction (NSTEMI). Methods: A total of 109 subjects were enrolled into the study, of whom 80 underwent coronary angiography (CA) with the diagnosis of NSTEMI and 29 had normal coronary arteries detected in CA. NSTEMI patients were divided into 2 groups: low SYNTAX score (< 32) (45 patients) and high SYNTAX score ( 32) (35 patients). Results: The NSTEMI patients with a high SYNTAX score (score  32) had a lower serum nesfatin-1 level (62 pg/ml; 39-98) compared to the NSTEMI patients with a low SYNTAX score (score < 32) (138 pg/ml; 65-286) and the control group (392 pg/ml; 178-1320). There was also a negative correlation between serum nesfatin-1 level and SYNTAX score (r = -0.594, p < 0.001). A lower serum level of nesfatin-1 (odds ratio = 0.116; 95% confidence interval: 0.138- 0.094; p < 0.001) was an independent predictor for high SYNTAX score in the NSTEMI patients after multiple linear regression analysis. Conclusions: Serum nesfatin-1 level was lower in the high SYNTAX group than in the low SYNTAX group in patients with NSTEMI. Nesfatin-1could have a role in the pathogenesis of atherosclerotic burden in patients with NSTEMI.