Adiponectin is one of the most important members of adipokine family which is widely synthesized and secreted by adipose tissue. The action of adiponectin is via binding to main receptors. It has several actions including regulation of glucose level, lipid homeostasis and reproductive system. Adiponectin can also influence vascular endothelium via preventing the migration of monocytes. The role of adiponectin has been detected in progression of certain cancers associated with obesity. Obesity is a risk factor for breast cancer and develops the progression of breast cancer, since adipocytokines are produced exclusively by adipose tissue and may influence the association between obesity and breast cancer risk. Therefore, it seems that obesity can play important role in the pathogenesis of breast cancer. The mechanism of adiponectin action in breast cancer is currently unknown. It seems that adiponectin motivates the sensitivity of peripheral tissue to insulin. Insulin can motivate the proliferation of breast cancer cells via signaling through insulin and insulin –like growth factor (IGF-1) receptors. Also insulin may upregulate a potent angiogenic agent including vascular endothelial growth factor (VEGF) expression that is secreted by breast cancer cells.