Melatonin (N-acetyl-5-methoxytryptamine) is secreted in the pineal gland and extra pineal tissues. Melatonin possesses a wide variety of biological effects such as chronobiological, sedative and anxiolytic. Melatonin may act as an antioxidant and a potent scavenger of both oxygen and nitrogen reactive molecules. The free radical scavenging activity of melatonin is receptor independent process whereas the indirect effect likely involves specific receptors . Melatonin stimulates the activity of enzymes involved in antioxidant defense and reduces the production of proinflammatory mediators [7,8]. Melatonin is a small, highly lipophilic and hydrophilic molecule. It passes freely through membranes and distributes in all subcellular compartments . These evidences suggest that these pleiotropic functions of melatonin may be used clinically under conditions where its circulating levels are reduced [9,10]. Because of its antioxidant, anti-inflammatory and anti-apoptotic effects, exogenous melatonin attenuates ischemia/reperfusion and hepatotoxins induced liver injury [11-13].