Introduction: Leptin, an anti-obesity hormone, is also a regulator of the immune response which sends important signals regarding the metabolic status and immune system function. This hormone/cytokine can affect the secretion of acute phase proteins such as Interleukin-1 and TNF-α and facilitate communication between nutrition and Th1 immune response so that when the food intake reduces, plasma leptin levels decreases, leading to reduced function of the immune system. Increase in blood leptin levels in obesity makes the obese people more susceptible to cardiovascular diseases, autoimmune diseases and cancer. Previous researches demonstrate the  important effects of leptin in metabolism, whereas more recent studies show that this molecule has an important role in many other key functions of body such as haematopoiesis, thermogenesis, reproduction, angiogenesis, homeostasis and immune system. This paper aims to review the most recent findings regarding the role of leptin in the pathology of autoimmune disease, in particular multiple sclerosis, psoriasis, autoimmune thyroid disease, lupus erythematosus, endometriosis and rheumatoid arthritis.