Distribution of various immunocompetent cells, i.e., IgG-, IgM-, IgA-, IgD-, IgE-, CD4-, and CD8-positive cells in palatine tonsils (tonsils) and pharyngeal tonsils (adenoids) of same patients were investigated immunohistologically by using monoclonal antibodies. The proportion of Ig-positive cells and T cell subsets in both tonsils were quantitatively studied by the image analyzer (CUE-2, Olympus, USA). The results were summarized as follows: 1) There was no significant difference in proportions of Ig-positive cells and T cell subsets between tonsils and adenoids. 2) IgG- and IgD-positive cells in the tonsils were significantly increased in cases with recurrent tonsillitis than in those with simple tonsillar hypertrophy. 3) Number of IgA2-positive cells were significantly changed, i.e., decreased in the subepithelial area of tonsils and increased in the interfollicular area of adenoids in cases complicated with otitis media with effusion. 4) In cases complicated with nasal allergy, IgE-positive cells were significantly increased in the interfollicular area in both of those tonsils and adenoids. These results indicate that the image analyzer will be a breakthrough in quantitative study on the immunohistology of tonsils and adenoids and give us useful informations about roles of the tonsil and the adenoid on the local immunity of the upper respiratory airway.