Alginate is a copolymer of beta-D-mannuronate and alfa-L-guluronate, which are present in the cell wall of brown algae. The hypocholesterolemic and hypolipidemic activities of alginate and its derivative,which is prepared by a reaction with octadecylamine, were compared in rats fed diets containing cholesterol and palm fat at 10 and 50 g/kg, respectively. Amidated alginate at 20 g/kg significantly decreased serum cholesterol from 2.93 to 2.00 mikromol/mL, serum triacylglycerols from 1.66 to 0.92 mikromol/mL, hepatic cholesterol from 17.5 to 5.9 mikromol/g, and total hepatic lipids from 67.4 to 51.7 mg/g. Alginate at 20 g/kg significantly reduced hepatic cholesterol to 13.1 mikromol/g, but did not influence serum cholesterol, triacyl-glycerols, and total hepatic lipids. Amidated alginate significantly increased the faecal concentrations of neutral sterols from 98.7 to 122.4 mikromol/g DM, but decreased faecal concentration of bile acids from 19.4 to 14.0 mikromol/g DM. In samples of intestinal contents, taurine-conjugated bile acids dominated glycineconjugates. The supplementation of diets with cholesterol significantly increased the expression of hepatic cholesterol 7 alfa-hydroxylase, especially in rats that received cholesterol without alginate or amidatedalginate. In conclusion, amidated alginate is an effective hypocholesterolemic agent that is more efficient than its parent polysaccharide.