Non-starch polysaccharides (NSP) and lignin are the principal components of dietary fibre. Legume seeds such as faba beans, peas, and lupins contain considerable amounts of non-starch polysaccharides. The average NSP content is 177 g in faba beans, 185 g in peas, and from 320 to 400 g/kg DM in different lupin species. Seeds of Lupinus angustifolius contain more NSP than seeds of Lupinus luteus and Lupinus albus. Differences among lupin species in the NSP level result from differences in the content of NSP sugar residues, particularly rhamnose, xylose, galactose, and uronic acids. Glucose and galactose constitute the main part of NSP sugar residues in lupin seeds. NSP of pea seeds and faba beans are mainly composed of glucose, arabinose and uronic acids. Dietary fibre of legume seeds may also include other components such as α-galactosides, resistant starch, polyphenols, and protein bound to cell walls. Different proportions of carbohydrates either hydrolysed by endogenous enzymes or fermented by gut microflora and of fat result in a different energy value of the legume seeds for animals. Since bacterial fermentation of NSP is more intense in the hind-gut of pigs, legume seeds have a higher energy value for these animals than for poultry. A high NSP content in animal diets negatively affects digestibility and nutrient absorption, while it may have beneficial dietary effects on humans. Different treatments, i.e. dehulling, microbial enzyme supplementation, are used to improve the nutritional value of legume seeds for monogastric animals.