Colonization of middle ear pathogens (S. pneumoniae, H. influenzae and B. catarrhalis), potential pathogens (S. aureus and coagulase-negative staphylococci) and non-pathogens was determined quantitatively on the posterior wall of the nasopharynx (NPH) of children (four age groups: under 2 years, 2–5 years, 6–10 years and 11–15 years). None of the 90 individuals examined was suffering at the time of bacterial sampling from acute otitis media (AOM), sinusitis, or tonsillitis. All individuals under 2 years of age harboured middle ear pathogens in the NPH, but only 40% of the individuals of the oldest age group (p < 0.001). Furthermore, in the youngest group, 57% of the cases had pathogens in the NPH, which completely dominated the bacterial flora, i.e. constituted more than 90% of the total bacterial count when calculated as CFU/cm². The corresponding count in the oldest age group was only 20% (p < 0.01). One important reason for the high incidence of AOM among young children in particular seems to be the noticeable accumulation of middle ear pathogens in huge quantities in the NPH in this age group.