Leptin is a hormone produced and secreted by adipose tissue. It is a member of adipokine family with a principal role in body weight regulation. It is reported that low brain leptin levels enhance the activity of hypothalamic orexigenic signals promoting feeding and suppressing energy expenditure and vice versa. Moreover, leptin via its three receptors participates in multiple neuroendocrine loops regulation. Serum leptin levels are positively associated with BMI (Body Mass Index) and whilst interact not only with other cytokines but also with serum insulin and cortisol levels. The aim of the present review is to study the role of leptin in carcinogenesis and its implications in cancer-related systemic inflammation.