We investigated the effects of fiber-rich wheat bran and wheat germ on dietary fat and cholesterol assimilation. Rats were given a test meal containing [14C]triolein and [3H]cholesterol. After various digestion periods, addition of the wheat fractions (10% of meal solids) did not modify the lipid gastric emptying rate. Gastric and intestinal triglyceride lipolysis was significantly reduced when wheat fractions were present. The mucosal uptakes of [14C]lipids and [3H]cholesterol were significantly modified by the wheat fractions after 1 and 2.5 h. No shift in the site of intestinal absorption and no change in the distribution of labeled lipid in the intestinal mucosa was observed. Plasma [14C]lipids and [3H]cholesterol were significantly decreased by both wheat fractions whereas these increased cecal accumulation of dietary lipids and cholesterol. Thus wheat bran and wheat germ alter fat and cholesterol processing in rats. A mechanism of action accounting for the data observed in proposed.