Objective: Metabolic syndrome (MS) was independently associated with increased risk of incident heart failure and coronary artery disease. In this study, we sought to identify whether there is an association between metabolic syndrome components and left ventricular diastolic functions and brain natriuretic peptide (BNP) levels. Materials and Methods: This study is a cross-sectional, observational study. Two hundred consecutive patients with MS were selected to form the study population. Echocardiographic parameters and BNP were determined. Mann-Whitney U test and Kruskal-Wallis test were used to compare BNP levels in categorical variables. Spearman rank correlation analysis was used to investigate the correlation between BNP level and other numerical variables. Linear regression analysis was used to find the variables affecting the BNP level. Results: BNP level was higher in females than males [11.14 (0.12-87) vs 7.49 (0.01-99) pg/dl, p=0.04]. None of the MS parameters affects the BNP level in MS patients. MS criteria number that the patient had was not related to BNP level. Sixty seven percent of patients had left ventricular (LV) diastolic dysfunction. BNP was independent from LV diastolic function. Multiple linear regression analysis demonstrated that having diabetes mellitus increases BNP level by 7.73 unit (β=7.73, 95% CI - 2.321 - 13.149, p=0.006). Conclusion: None of the MS parameters affects the BNP level in MS patients. Diastolic dysfunction existence did not affect the BNP level of MS patients. There is an association between diabetes mellitus and BNP, independent of left ventricle diastolic functions.