Colonization of the porcine gut microbiota commences after birth; however, this development is interrupted at weaning, rendering the piglet vulnerable to enteric disease. Dietary supplementation of non-digestible oligosaccharides can contribute to the stabilization of gut homeostasis by promotion of saccharolytic bacteria, inhibition of opportunistic pathogens, bacterial metabolite production and immune regulation. Whilst traditionally fructans and galactooligosaccharides have been added to weaner pig diets, supplementation of sow’s gestation and lactation diets and oral administration of suckling piglets may exert some beneficial effects too to promote gut microbiota and (immune) function development. Oligosaccharides in sow milk act as prebiotics by specifically shaping the gut microbiota of the offspring. This chapter summarizes the current knowledge on effects of prebiotic oligosaccharides on porcine gut function and health. The modes of actions of those substances are discussed as well as aspects that need more investigation for future applications in diets for suckling piglets.