Polysaccharides are widespread biopolymers, which quantitatively represent the most important group of nutrients in botanical feed. In animal nutrition polysaccharides, which cannot be degraded by endogeneous enzymes and therfore reach the colon almost indigested, are summarized as "non-starch-polysaccharides (NSP)". Individual NSP groups have different chemical and physical characteristics, that result in various effects on physiology of intestine and on organism in general. They affect e.g. digesta passage, nutrient resorption, microbial growth and activity, lipid metabolism and immune systeme. The physiological effects lead to conclusion that some polysaccharides are suitable tools in health management of farm animals. However, limitations result from antinutritive effects and from little scientific knowledge about modes of action in vivo.