PIP60-1, a novel heteropolysaccharide isolated from fruiting bodies of the medicinal fungus, Phellinus igniarius, has a molecular weight of 1.71 x 10(4)Da and is composed of L-fucose, D-glucose, D-mannose, D-galactose and 3-O-Me-D-galactose in a ratio of 1:1:1:2:1. A structural investigation of PIP60-1 carried out using sugar and methylation analyses, combined with (1)H and (13)C NMR spectroscopy, including COSY, TOCSY, NOESY, HSQC and HMBC experiments, established the repeating unit of the polysaccharide as the following: [structure: see text]