Interleukin-8 induces chemotaxis of neutrophils, basophils and T-lymphocytes, releases intracellular enzymes from neutrophils and histamine from basophils, and regulates the adhesion of neutrophils. In this study, using an enzyme-linked immunosorbent assay, we evaluated 33 middle ear effusions (MEEs) for levels of IL-8. The mean level of IL-8 in MEEs from children with OME was 616.7 +/- 211.0 pg/mgTP, while that of adults was 197.4 +/- 66.7 pg/mgTP. With respect to MEE types, the mean level of IL-8 in serous effusion was lower than that in two other types of MEEs (mucoserous and serous). These results suggest that inflammatory reaction in the middle ear cavity of children with OME is different from that of adults and that the pathogenesis of OME in children may differ from that in adults. Determination of IL-8 concentration in MEEs may help to illuminate the pathogenesis of OME.