It has been previously reported that ethanol alters the level of polyunsaturated fatty acids, and this may be related to alteration of membrane physical properties. Therefore, developing a technique to efficiently analyze lipid molecular species is of value for alcohol research. A new technique which can provide detailed structural information for most major lipid classes has been developed in our laboratory using thermospray liquid chromatography/mass spectrometry (LC/MS). In this technique, on-line LC separation is achieved with a conventional flow rate and the LC effluent is carried into the mass spectrometer via a heated capillary where it is vaporized and ionized. The results thus obtained for the major lipid classes including fast separation methods and quantitative aspects will be presented.