The oligosaccharides from the lipopolysaccharides of Moraxella catarrhalis serotype B, strain CCUG 3292, were isolated after mild acid hydrolysis and separated by high-performance anion-exchange chromatography. The structures of the oligosaccharides were established by fast atom bombardment mass spectrometry and nuclear magnetic resonance spectroscopy. It is concluded that the oligosaccharides comprise a mixture of mainly a nona- and a deca-saccharide. [GRAPHICS] Smaller amounts of undecasaccharides and of truncated forms. namely, hexa-, hepta-, and octa-saccharides, were also detected. (C) 1996 Elsevier Science Ltd.