Biological membranes are a vital component of all living cells. They consist mainly of lipids and proteins. The proteins are embedded into the lipid structure, whose distribution in an aqueous environment forms a bilayer. The biological membranes have an average thickness of 30Å, determined by the size of the carbon chain of lipids, which range from 14 to 24 carbons. The lipid portion of biological membranes is also fundamental to determine their physicochemical properties such as membrane order, fluidity, and hydrophobicity. As Alzheimer’s disease pathology is mainly due to actions of Aβ peptides on the plasma membrane, its modifications are of great importance. In fact, membrane lipids, such as cholesterol, ceramides, gangliosides, and fatty acids, have been implicated in the molecular mechanisms of various stages of Alzheimer’s disease pathology. The following chapter describes the main changes in membrane lipid composition in Alzheimer’s disease (AD).