In the present the exact pathogenesis of otitis media with effusion was not fully known although there were a number of etiologic theories. But it has become increasingly evident that bacterial flora of nasopharynx play a crucial role in the pathogenesis of otitis media with effusion, especially, bacterial attachment of nasopharynx is now being attended. In the clinical experience, there was large number of chronic rhinosinusitis accompanied with otitis media with effusion in the early childhood and it was well known that nasopharyngeal pathogen in accordance with pathogen of chronic rhinosinusitis. But it is not proven how chronic rhinosinusitis influences on the occurrence of otitis media with effusion. With conventional bacterial culture method it may very difficult to distinguish the attached bacterial species from nonattached one which are just floating over the mucosa because that merely indicated floating bacteria in the mucous film covering the epithelium. So, we intended to observe whether nasopharyngeal bacterial attachment is related to otitis media with effusion and it is increased in rhinosinusitis. Normal control group and otitis media with effusion group who were not on the antibiotics at least 3 month previously, were included and observed bacterial attachment of nasopharynx. Normal control group exhibit more bacterial attachment than patient group and decreased with age. But there was no significant statistical difference between otitis media with effusion and chronic rhinosinusitis group.