Water-soluble fiber has been reported to reduce serum cholesterol and consequently, oat bran, which has a high soluble-fiber content, has been recommended as part of a lipid-lowering diet. However, a recent small study of 20 volunteers with low mean serum cholesterol concentrations (4.8 mmol/L) demonstrated no lipid-lowering effect of oat bran. The present study investigated 64 volunteers with cholesterol concentrations much more typical of the UK population (6 mmol/L). Subjects were randomly allocated to receive either a normal-sized helping of an oat-based cereal or a cereal containing no oats for 4 wk and then crossed over to the alternative regimen for a further 4 wk. Small (2.23% and 4.55%) but significant (P < 0.04 and P < 0.05) reductions in total and low-density-lipoprotein cholesterol, respectively, were observed in association with the consumption of oat-based cereal. These data support the view that consumption of oat-based cereals may well contribute usefully to a lipid-lowering diet.