Human mucus was isolated from faecal samples of newborns, two and six month old infants and adults. The adhesion to this mucus by the bacteria mentioned below was assessed in vitro. Depending on the age group: 44-46% of the applied Lactobacillus GG, 23-30% of Bifidobacterium lactis Bb-12, 9-14% of Lactobacillus johnsonii LJ-1, 3-10% of Lactobacillus salivarius LM2-118, Lactobacillus crispatus M247, Lactobacillus paracasei F19 and 2% of L. crispatus Mu5 adhered. All the strains adhered better to the mucus of adults than to that of infants. With some of the strains significant differences between the infant age groups were also observed. In conclusion, the age of the target group may be worthy of consideration when planning a schedule for probiotic or functional food therapy.