This article by the ESPGHAN Committee on Nutrition summarizes available information on the effects of adding prebiotic oligosaccharides to infant and follow-on formulae. Currently there are only limited studies evaluating prebiotic substances in dietetic products for infants. Although administration of prebiotic oligosaccharides has the potential to increase the total number of bifidobacteria in feces and may also soften stools, there is no published evidence of clinical benefits of adding prebiotic oligosaccharides to dietetic products for infants. Data on oligosaccharide mixtures in infant formulae do not demonstrate adverse effects, but further evaluation is recommended. Combinations and dosages in addition to those so far studied need to be fully evaluated with respect to both safety and efficacy before their use in commercial infant food products. Well-designed and carefully conducted randomized controlled trials with relevant inclusion/exclusion criteria, adequate sample sizes and validated clinical outcome measures are needed both in preterm and term infants. Future trials should define optimal quantity and types of oligosaccharides with prebiotic function, optimal dosages and duration of intake, short and long term benefits and safety. At the present time, therefore, the Committee takes the view that no general recommendation on the use of oligosaccharide supplementation in infancy as a prophylactic or therapeutic measure can be made.