Interleukin-6(IL-6) is a multifunctional cytokine that regulates the immune response, acute phase reactions, and hematopoiesis. It is involved in induction of B-cell differentiation and induction of acute phase proteins. Intercellular adhesion molecule-1(ICAM-1) is an adhesion molecule expressed in high endothelial venules(HEVs) in humans, that is involved in the interactions between leukocytes and endothelial cells. ICAM-1 also plays a critical role during an inflammatory response in the interaction between activated endothelium and immunocompetent cells. Human tonsil specimens were stained by immunohistochemical method to compare the expression of IL-6 and ICAM-1 with the degree of tonsillar hypertrophy, age, and growth status. In addition, the correlation between eapression of IL-6 and ICAM-1 was studied. The results were as follows : 1) IL-6 was highly expressed on endothelial cells, plasma cells, and lymphocytes. 2) ICAM-1 was mainly expressed on lymphocytes in interfollicular areas and partially expressed on lymphocytes in germinal centers. 3) The expression of IL-6 and ICAM-1 was increased as the grade of tonsillar hypertrophy became high(p<0.05). 4) The expression of both IL-6 and ICAM-1 were slightly increased before puberty(p<0.05). 5) The expression of ICAM-1 was along as the exprssion of IL-6 became increased(p<0.05). This study showed that interaction of IL-6 and ICAM-1 was partly involved in tonsillar hypertrophy in recurrent tonsillitis of children.