Technical Abstract: The healthful, cholesterol-lowering (atherosclerosis amelioration) or detoxification of harmful metabolites (cancer prevention) potential of cereals and cereal fractions could be predicted by evaluating their in vitro bile acid binding under physiological conditions. Using equal dry matter per incubation the in vitro bile acid binding relative to cholestyramine (cholesterol-lowering bile acid binding drug) was rice bran 25%, wheat bran 20%, oat bran 5% and corn bran 3%. Using equal total dietary fiber per incubation, relative bile acid binding on dry matter basis was rice bran, 12%; oat bran, 4%, barley, 5%; and beta-glucan enriched barley, 6%. Relative bile acid binding of wheat bran unextruded (WBU) and extruded wheat bran at various specific mechanical energy (SME) levels 120-358 Whr/kg dry matter was on dry matter basis was WB-177, 23%; WB-120, 21%; WBU, 18%; WB-234, 17%; WB-291, 17% and WB-358, 14%. The relative bile acid binding on dry matter basis for the milled wheat bran (MWB) and milled and extruded at SME 120-358 Whr/kg was MWB, 21%; MEB-177, 21%; MEB-358, 21%; MEB-120, 19%; MEB-234, 19% and MEB-291, 18%. The mean relative bile acid binding values for single grain wheat, oat, rice and corn cereals were 9.4, 8.6, 2.8 and 2.1%, respectively. Bile acid binding was not proportional to the soluble fiber content of the oat bran and barley fractions tested. Similar bile acid binding of rice bran and wheat bran suggest that rice bran should be tested for its cancer prevention potential. Process technologies milling, rolling, extrusion, shredding, toasting, flaking and fortification would enhance healthful potential of cereals and cereal fractions. Bile acid binding by rice bran may account to a great extent for its cholesterol-lowering properties, while bile acid binding by wheat bran may relate to its cancer prevention potential.