Although the advantages of in vitro n.m.r. analysis of cellular lipids have been documented, this purely n.m.r. approach also has drawbacks. Rapid and quantitative separation of total lipids into neutral lipids, non-esterified fatty acids, non-acidic phospholipids and acidic phospholipids using Bond Elut ion-exchange columns as demonstrated here permitted a more quantitative and complete n.m.r. analysis of glycerides, cholesterol, saturated and unsaturated sphingolipids and ether lipids, as well as of diacylcholine and ethanolamine lipids. Acidic lipids were also analysed. The fatty acid compositions of the intact lipids in each of the four Bond Elut fractions were determined from the n.m.r. spectrum of each fraction.