Dietary fibres (DF) have been isolated from rapeseed and peas, separated into different fractions and investigated for their content of associated non-carbohydrate compounds, especially proteins by UV-spectroscopy, nitrogen determination, isoelectric focusing, and rocket Immunoelectrophoresis. The level of protein varied according to the plant origin of DF and among the different DF fractions (pectins, hemicelluloses, cellulose, lignins). In general, rapeseed DF contained more protein than pea DF, with the hemicellulose fraction from rapeseed hulls having the highest level. Rocket immunoelectrophoresis proved the presence of myrosinase as part of the DF associated proteins in rapeseed. This may be of importance for the degradation of glucosinolates in the digestive tract of humans and animals, and thereby the effects from these compounds are changed.