The pathophysiology of otitis media with effusion(OME) is a challenging problem in the field of otology. To investigate the correlation between OME and inflammmatory reaction of adenoid, we compared statistically the number of adenoid mast cells in the OME group to that of the nonOME group. The distribution of mast cells in the adenoidectomy specimens of 48 children with enlarged adenoid was studied. Thirteen cases of the patients had OME, and the remaining 35 had normally aerated middle ears. The number of mast cells was 91 in the patients with secretory otits media and 45 in the control group. Statistical analysis disclosed the significant difference(Z=0.0011) in mast cell number between the two groups, however there was no statistical difference in adenoid-nasopharyngeal(A/N) ratio between the two groups. The results of the study support that the adenoid inflammatory mediator relese hypothesis may be also an important factor in the pathogenesis of secretory otitis media.