Human milk oligosaccharides play an important role, as prebiotic soluble fibres, in the postnatal development of the intestinal flora. Infant formulas are virtually free of prebiotic oligosaccharides. As a consequence, formula-fed infants develop an intestinal flora significantly different to the flora of breastfed infants. Due to the complexity of human milk oligosaccharides, it is necessary to use alternative sources of prebiotic ingredients as components of infant formulas. The present review summarizes the data of experimental research and clinical studies with a prebiotic mixture containing 90% short-chain galacto-oligosaccharides and 10% long-chain fructo-oligosacchrides are summarized. The data demonstrate that, with this prebiotic mixture, the growth of bifidobacteria and lactobacilli can be stimulated, the faecal pH can be decreased, and the presence of pathogens can be reduced to levels similar to those of breastfed infants. Thus, prebiotic oligosaccharides such as the studied mixture provide beneficial effects for formula-fed infants.