Lipids were extracted from adult Onchocerca gibsoni with chloroform/methanol and the total lipid content was characterized. Glycolipids were isolated from other lipid classes by Florisil column chromatography and were then fractionated by DEAE-Sephadex ion-exchange chromatography. HPTLC revealed the presence of 9 neutral glycolipid bands and of 15 acidic glycolipid bands that stained for sialic acid with resorcinol. Lipids that contained no carbohydrates were analyzed by a combination of TLC and amino column chromatography. Triacylglycerols, cholesterol, cholesterol esters, and free fatty acids were found to be major components of the neutral lipid fraction, and diacylglycerols and monoacylglycerols were minor components. Phosphatidylethanolamine and phosphatidylcholine were the predominant phospholipids. Phosphatidylserine, phosphatidylinositol, sphingomyelin, lysophosphatidylcholine, and lysophosphatidylethanolamine were also present in significant amounts, whereas only traces of cardiolipin and phosphatidic acid were detected. Several minor lipids and phospholipids remained unidentified. These results indicate that adult O. gibsoni have a nonglycosylated lipid composition resembling that of other parasitic nematodes as well as a substantial repertoire of glycolipids, including many with the characteristics of gangliosides.