Recurrent otitis media may be related to defects in specific antibody production, as suggested previously. This might be reflected in lower antibody responses to vaccinations administered in the context of the national childhood vaccination program in children suffering from recurrent otitis media. In a cross-sectional study we determined the levels of antidiphtheria, antitetanus, anti- Haemophilus influenzae type b (anti-Hib) and antimeasles antibodies in sera of 163 children with two or more episodes of acute otitis media per year and in 143 children with repeated periods of persistent otitis media with effusion each lasting at least 3 months. The control group consisted of 521 age-matched healthy children, who were free of recurrent respiratory tract infections. Children with recurrent acute otitis media, including highly otitis-prone children, showed higher antidiphtheria and antitetanus antibody titers compared to controls. No differences were observed in anti-Hib and antimeasles antibody levels between children with recurrent acute otitis media and controls, nor did any of the antibody levels in children with persistent otitis media with effusion differ from those in controls. Therefore, the results of our study do not point toward a generalized immunological hyporesponsiveness in children with recurrent acute otitis media and persistent otitis media with effusion. Determination of antibody responses to regular vaccines is not indicative for otitis-proneness.