Background: Coronary artery disease (CAD) represents the leading cause of death worldwide. Animal and human studies have demonstrated that silent information regulator 1 (SIRT1) is involved in a wide range of physiological and pathological processes. This study aimed to measure the plasma level of SIRT1 in patients with CAD and explore its correlation with cardiovascular risk factors. Results: Plasma SIRT1 was signifcantly lower in patients with chronic coronary syndrome (CCS) than in those in the control group and was signifcantly lower in patients with both acute myocardial infarction and unstable angina than in those in the control group and with CCS. Moreover, plasma SIRT1 was positively correlated with platelet count and negatively correlated with cholesterol and triglyceride levels. Conclusions: The plasma level of SIRT1 is lower in patients with CAD compared to control and it could be a possible marker for this disease. Multi-center studies with follow-up measurements are recommended for further investigation.