Background: Arterial hypertension is one of the leading causes of mortality and morbidity in general population. Sirtuin 1 (SIRT1) has diverse anti-inflammation, anti-oxidant, and anti-apopytosis effects on endothelium and is associated with endothelial aging and dysfunction. The objective of this study was to evaluate the relation of serum SIRT1 level with left ventricular hypertrophy (LVH) in newly diagnosed hypertensive patients. Methods: One hundered and twenty-five consecutive, newly diagnosed hypertensive patients were divided into two groups with regard to presence of LVH and compared to 40 healthy control subjects. LVH was determined by transthoracic echocardiography using the cube formula. Serum SIRT1 level was analyzed with enzyme-linked immunosorbent assay. Results: Serum SIRT1 level was significantly higher in patients with LVH compared to those without LVH (14.3 +/- 3.9 ng/ml vs. 7.9 +/- 3.6 ng/ml, P < 0.001) and healthy control subjects (14.3 +/- 3.9 ng/ml vs 6.6 +/- 2.0 ng/ml, P < 0.001). Multivariate logistic regression analysis revealed higher serum SIRT1 level independently predicted LVH in hypertensive patients (OR 1.50; 95% CI, 1.30-1.73; P < 0.001). Receiver-operating characteristic curve analysis demonstrated a cutoff value of 9.4 had a sensitivity of 90% and specificity of 74% for the prediction of LVH (AUC 0.885; 95% CI, 0.815-0.935; P < 0.0001). Conclusion: SIRT1 was a powerful biomarker for predicting LVH in hypertensive patients.