The O-specific polysaccharides of Xanthomonas campestris pv. vignicola GSPB 2795 and GSPB 2796 were studied by sugar and methylation analyses, Smith degradation, 1D, 2D 1 H and 1 3 C NMR spectroscopy. It was found that the polysaccharides are similar branched d-rhamnans lacking strict regularity, and their structures can be described as follows:where Rha V is present in a non-stoichiometric amount, which varies from strain to strain.