The etiology of otitis media with effusion is still unsettled. In particular the role of allergy has received conflicting support with widely varing opinions as to its importance. Within recent years; stiking biochemical and immunochemical analytic techniques have opened a new approach to the study of otitis media with effusion. We have analysed middle ear fluids from 36 ears(28 patients) by comparing immunoglobulins of the fluid with patients' serum. The allergic tests were also done in 14 patients suspected of nasal allergy by history and physical examination. The obtained results were summarized as following; 1) In 28 patients, there were 14 patients(50%) suspicious of nasal allergy by history and physical examination, and there were 4 patients(14%), 8 ears(22%) in 36 ears, who were positive of allergic tests. 2) In 36 ears, serous fluids were obtained from 20 ears(56%), and mucous fluids were obtained from 16 ears(44%). In 4 patients(8 ears) who were positive of allergic tests, both serous and mucoid fluids were obtained from each 2 patients(4 ears). 3) The concentrations of IgG and IgA in the middle ear effusion were higher than those in the serum (p<0.05), and the concentration of IgE in the middle ear effusion was relatively equal to that in the serum(p>0.05). 4) The concentrations of Immunoglobulin were not significantly affected by allergy or the character of middle ear effusion.