AbstractDuring the last ten years, considerable advances have been made in the application of infrared spectroscopy to the study of lipids. This work reviews this contribution.Starting with a brief discussion of the basis of the technique, applications of a qualitative and quantitative kind are described. The lipids discussed include the simple fatty acids, alcohol esters, then the more complicated glycerides, cholesterol esters, soaps, phospholipids, lipoproteins, and finally some recent studies of the myelin sheath.