Evaluate possible role of Helicobacter Pylori in pathogenesis of otitis media with effusion (OME). Randomized controlled trial, tertiary referral center. Middle ear fluid was aspirated, a biopsy was taken from the promontorium of 22 children with OME. A small biopsy was taken from the promontorium of 20 children with normal otologic findings. For both groups, 5 mm deep tissue specimens were obtained from tonsil and adenoid. H pylori presence in the middle ear, the tonsillar and adenoid tissues by culture and PCR was significantly more frequent in the study group compared to the control group (P<0.05). This study is the first to grow H pylori in middle ear in OME. Significantly increased colonization by H pylori of the middle ear, and tonsillar and adenoid tissue in patients with OME indicates that the bacteria might be involved in the pathogenesis of OME. A-1b.