The hypolipidemic effect of an exo-biopolymer (EBP) produced from a submerged mycelial culture of the mushroom fungus, Auricularia polytricha, was investigated in the dietary-induced hyperlipidemic rats. In a dose-dependent study, the EBP was fed at 50-100 mg kg(-1) body weight and significantly decreased the concentrations of the plasma triacylglycerols, total cholesterol, and low-density lipoprotein (LDL) cholesterol. The plasma LDL cholesterol concentration was decreased up to 70%. Production of A. polytricha biomass and EBP were optimal at pH 4 with maximum growth at 20 degreesC and EBP production at 30 degreesC. Gel chromatography of the EBP revealed a single peak of a glycoprotein with a molecular size of 32 kDa. It contained 77.5% carbohydrate and 22.5% protein. The sugar and amino acid compositions of the EBP were analyzed.