LPS have been isolated from 6 strains of Rahnella aquatilis, their separate structure components have been obtained: lipid A, O-specific polysaccharide shain (OPS) and core oligosaccharide. 3-Oxytetradecanoic (31.7%) and tetradecanoic (17.8%) acids are dominating fatty acids of the lipid A. The core oligosaccharide of most investigated strains includes galactose and glucose, some of them include arabinose and ribose. Glucose, mannose and galactose are dominating monosaccharides in the composition of OPS of the strain 33071, fucose and galactose--in OPS of the strains 1-95, 2-95, 2-87 and 3-88, mannose in the composition of strain 3-95 OPS.