This is a follow up study of a multicenter randomised placebo-controlled trial in seven centres in five West European countries. The RCT assessed the effect of infant formula supplemented with a mixture of prebiotics (with neutral short-chain and long-chain oligosaccharides and pectin-derived acidic oligosaccharides) during infancy in term-born children (n=1130). In the follow-up study 672 children (60% of the study population) participated: 232 (56%) from the prebiotics group (PG), 243 (58%) from the control group (CG), and 197 (66%) from the non-randomised breast-fed group (BG). The primary outcome was the occurrence of febrile episodes at three to five years of age prospectively documented by the parents: in the PG 1.17 (interquartile range 0.50-2.08) episodes per year versus 1.20 (0.52-2.57) in the CG; and 1.48 (0.65-2.60) in the BG. This specific prebiotics mixture given during infancy in healthy non-atopic subjects does not decrease febrile episodes and therefore seems not to prevent infection between their third and fifth birthday.