Thirty-one children, 2.6-12.2 years (mean = 7.9 +/- 5.0) were divided into four clinical categories: normal controls (n = 7), recurrent tonsillitis (n = 8), idiopathic tonsillar hyperplasia (n = 9) and recurrent tonsillitis with hyperplasia (n = 7). Immunohistopathologic studies were performed to determine the presence and location of HLA-DR, S-100 positive antigen presenting dendritic cells (DCs) in six microanatomic compartments: surface and crypt epithelium and submucosae, extrafollicular areas and lymphoid follicles. The results were analyzed in the context of the clinical history, bacteriology, and routine histopathology. The distribution of DCs was altered significantly with disease fewer numbers of DCs were found in the surface epithelium and greater numbers in the crypts and extrafollicular areas, than in normals, p <0.01. The surface : crypt ratio of DCs was 1:1 for normal tonsils, but dropped to 1:3 in disease. Chronic cryptitis was more common in disease and correlated strongly to the presence of beta-lactamase producing microorganisms (R = 1.0). An increased total bacterial concentration was correlated with increased numbers of DCs in the surface epithelium (R = 0.5, p <0.009). In summary, the microanatomical distribution of DCs within the tonsil is significantly altered in disease. These alterations appear to be influenced by potentially pathogenic bacteria more often found in the crypts of abnormal tonsils.