Alteration of lipid metabolism plays a critical role in the development of many types of cancer including breast cancer. Lipid metabolism can be regulated by a variety of signaling pathways with proliferative stimuli, apoptotic stimuli or environment changes under physiological, pathophysiological or therapeutic conditions. On the other hand, many lipids and lipid intermediate metabolites are also important signaling molecules involved in cell signaling that regulate cell proliferation, differentiation, apoptosis and migration as well as responses to drug treatment. In physiological condition, lipid metabolism (anabolism and catabolism) is tightly regulated by signaling network in the cell under designed path to growth, proliferation, differentiation and migration. Dysregulation of lipid metabolism under pathological condition leads to alteration of lipid profiles and accumulation of some "bad" lipids which can cause cell overgrowth and hyper-proliferation such as cancer and cell death such as tissue injury (Fig. 8.3). This chapter focuses on the emerging understanding of the role of lipid metabolic pathway in breast carcinogenesis and tumor progression. The update information indicates that the modulation of lipid metabolism can potentially be exploited to prevent breast cancer and enhance efficacy of breast cancer therapy.