Lymphocytes in the lingual tonsil were analyzed using monoclonal antibodies to cell surface markers. Immunohistologic staining of lingual tonsillar tissue showed localization of the various lymphocyte subsets in the germinal center, mantle zone, and inter-follicular area. Populations of lymphocyte subsets, i.e., T cells, B cells, CD4 positive cells, CD8 positive cells, alpha beta T-cells, gamma delta T-cells, and NK cells were assessed by laser flow cytometry analysis, and we compared the following tissues: peripheral blood, lingual tonsils, palatine tonsils, and pharyngeal tonsils (adenoids).