Although the pathogenesis of otitis media with effusion(OME) is not clearly indentified, various biochemical, immunological and bacteriologic parameters contribute to the generation of effusion during otitis media. Lysozyme has been known to act not only as a member of first of defense against invading microorganisms, but also as a viscoelastic promoter. It has been suggested that changes in biochemical parameters of body fluids might reflect disease processes of the middle ear cavity taking place in otitis media and the pathogenesis of biochemical parameters for OME, lysozyme and protein concentrations were determined in MEE and serum of patients with OME. Results were as follows : 1) The total of fifty cases of otitis media with effusion comprised 43 cases(86%) in children and 7 cases(14%) in adults. The high incidence rate of children was due to cleft palate patients between 0 and 2 years old. 2) Lysozyme concentration was significantly higher in middle ear effusion than in serum(p<0.05) in various forms of effusions studied. Also, lysozyme concerntration in MEE was significantly higher in mucoid otitis media than in serous otitis media(p<0.05). This phenomenon indicates that the lysozyme is a local product of inflammatory reactions in midddle ear cavity and plays another significant role in relation to viscoelastivity of middle ear effusion. 3) There was significant differences of lysozyme in MEE in all forms of effusion studied between non-cleft palate group and cleft palate group(p<0.05). 4) There was significant differences of lysozyme in serous effusion between non-chronic sinusitis group and chronic sinusitis group(p<0.05). 5) There was significant differences of total protein level in MEE between non-recurrence group and recurrence group(p<0.05). These results indicate that lysozyme and protein play an important role in the disease process, chronicity and.or the tendency of recurrence of otitis media. In the base of this study, it is helpful in guidelines for better treatment and prevention of recurrence for middle ear effusion.