An analysis of the released oligosaccharides from a membrane glycoprotein preparation of third instar larvae (3rdIL), and purified larval serum protein 2 (LSP2) from Drosophila melanogaster was performed. Sequential exoglycosidase digestion in combination with high-resolution gel permeation chromatography and partial acetolysis indicated the presence of two series of oligomannosides; one of these series was unusual and characterized by the presence of a core alpha 1-6 linked fucose, the other was a typical mammalian oligomannose series containing the following isomers -D1, -D2, -D12, -D123 and -CD123 as well as the unprocessed Man9GlcNAc2 structure. Conventional oligomannose could only be detected in the LSP2 sample. This study opens the way to use powerful molecular and classical genetic techniques to analyse the control and functional significance of glycosylation in higher organisms.