Dietary fibres (DF) are mainly plant cell wall constituents or plant materials resistant to hydrolysis catalysed by enzymes secreted from mammalian cells in the first part of the mammalian digestive tract. Our interest in DF is directed at physiological effects caused by DF; their effects on nutrients and non-nutrients including xenobiotics, and effects on the structure and composition of digesta including the microflora in the digestive tract. This means that DF have several both positive and negative effects on the quality of food and feed depending on the type of DF, and as DF are a necessary or important part of all high quality foods and feeds, focus should be placed on obtaining more exact structural information on DF. The chemical composition and structure of DF, their physico-chemical properties and physiological effects comprise therefore an area of increasing interest. In consequence thereof, we have placed specific focus on all parts of DF, not only the carbohydrates, but all DF constituents which give a contribution to the binding properties of DF toward nutrients and non-nutrients. These studies of DF have required investigations based on isolated DF, and it is found, that the unsolved problems, which also require a solution, are the questions of possible differences in effects in food/feed matrixes of isolated DF and indigenous DF. However, the research needs in all cases to be focused on the information required with respect to structure and properties of DF. Such investigations must be based on analytical methods, and the level of information obtainable therefrom can, as other systematic biochemical-natural product chemical research studies, be divided into 4 levels denoted as the 4 x C: 1. Composition: types of carbohydrates, lipids, proteins, phenolics and other compounds in DF; 2. Constitution: structure of the DF compounds and DF itself 3. Configuration: stereochemistry of DF/DF components: 4. Conformation: the actual or preferred spatial structure of the solvated DF. In systematic DF studies of this type, the sequence needs to be from information level 1 to level 4, and the last three levels of information are important for an understanding of the binding properties or physiological effects DF may have.