**Abstract**

Melatonin is an endocrine product released from the gland known as the pineal gland and is predominantly secreted during the night. Light exerts an inhibitory effect on melatonin secretion in the pineal gland. The suprachiasmatic nucleus controls pineal melatonin synthesis and its release *via* the peripheral sympathetic nervous system, which includes synapses in the intermediolateral cell column of the thoracic cord and its projection toward the superior cervical ganglia. Melatonin regulates many physiological functions in the body through membrane receptors and nuclear binding sites. In a chick study, the presence of melatonin receptors in cardiomyocytes was reported and, in another study, MT1 and MT2 membrane receptors were identified in left ventricular cardiomyocytes of the human heart. For this reason, it is suggested that melatonin has some regulatory effects on the cardiovascular system. Ischemic heart disease and myocardial infarctions are the main cause of cardiovascular death. Studies have shown that melatonin applications reduce the amount of blood cholesterol, LDL, and triglyceride and increase the amount of HDL. In light of these data, it can be said that melatonin is an important cardiovascular system protector. In this chapter, the protective effects and mechanisms of melatonin on the cardiovascular system will be discussed.

**Keywords:** melatonin, cardiovascular diseases, heart, antioxidant, anti-inflammatory
