The article reviews literature data and results of own investigations concerning biological properties of low digestible carbohydrates (LOOs): lactulose, inulin and different type of oligosaccharides. The following problems: (1) sources of oligosaccharides in animal and human diets, (2) behaviour of oligosaccharides in the gastrointestinal tract, (3) physiological effect of LOOs in diets for laboratory rodents, (4) physiological effect of LOOs in diets for non-ruminat livestock and (5) nutritional advances of LOOs in diets for human were presented. The above-mantioned reports indicate that oligosaccharide preparations can be considered as feed additives in pigs and poultry feeding, e.g. being as effective as antibiotics in the control of pathogens and enhancement of growth performance. However much more research are needed to determine the appropriate role of these oligosaccharides in animal feeding. LDOs may influence animals and humans in various ways: improve intestinal health, modify lipid metabolism, modulate the immune response, and decrease the risk of intestinal and systemic diseases. The present state of knowledge on mechanism of dietary action of prebiotic LDOs and physiological effects of different types and doses of low-digestible carbohydrates is not sufficient.