Levels of cytokines, interleukin (IL)-1 alpha, IL-1 beta, tumor necrosis factor (TNF), and granulocyte-macrophage colony-stimulating factor (GM-CSF) were investigated in samples of the middle ear effusions (MEEs) from 144 ears with otitis media with effusion (OME) by enzyme-linked immunosorbent assay, followed by cytologic analysis. Middle ear effusions of the acute purulent type contained a significantly higher concentration of cytokines compared with normal control sera (p < .001). Cytokines were observed at lower levels in MEE in adults than in children. Tests of children at the chronic stage of MEE showed higher levels of TNF than IL-1 and GM-CSF. Meanwhile, IL-1 beta showed significantly higher concentrations in acute purulent types than in serous and mucoid types (p < .01). In cytologic analysis, the mean level of IL-1 beta was significantly higher in the neutrophil-rich group than in other groups (p < .05). Cytokines possess several biologic properties, some of which are associated not only with acute otitis media but also with chronic otitis media. This study showed that cytokines, especially IL-1 beta, contribute to infiltration into the middle ear by inflammatory cells. This implies that the persistent presence of cytokines in MEE could be a factor in prolonged OME.